Blitting the Night Away: Nichibutsu's Mahjong Koi no Magic Potion

Imagine, if you will, a young man. So desperate for a cure for his disease, that he seeks out a time machine to travel to a future where a cure might exist. But whenever he approaches someone, they insist on playing the tile game mahjong, and for some reason the women start interrogating him about their bodies as they take off their clothes. Will he ever find his cure? This is the story of Mahjong Koi no Magic Potion. No, really.

Top of the Industry

There were a lot of companies that did strip mahjong. Mitchell, Jaleco, Seta, Toaplan, Capcom, Psikyo, nearly everyone at least gave it a dabble. But the one company above them all is the one who came up with the whole idea, Nichibutsu. Nichibutsu wasn’t just the first company and the last company in the arcade strip mahjong business, they were almost certainly the most prolific. Like seriously, they made a ton of these.

And today’s game is a perfect example of Nichibutsu’s arcade mahjong hardware. None of them have names; Koi no Magic Potion was released in 1992, and MAME groups Nichibutsu games between 1991 and 1995 into a single driver in MAME, but that seems to be a MAME thing. Overall this hardware just seems to have been tweaked and changed over time without regard for creating a single family. This was hardware made en masse for games with a short shelf life.

For CPU power, Mahjong Koi no Magic Potion uses two Toshiba TMPZ84C011 CPUs. The TMPZ84C011 is a surface-mount, CMOS version of the famous Zilog Z80, and the C011 means that Toshiba included a few I/O ports built-in. To the internal CPU core, these are mapped to some of the Z80’s existing I/O port, so from a programmer’s perspective, the TMPZ84C011 is just a Z80. You might compare it to the Commodore 64’s 6510 CPU, which adds an I/O port to the famous 6502.

Sound

The first of those Z84C011’s, running at apparently a whopping 8MHz, handles the sound. A Z80 (~ish) for a sound CPU is nothing new in 1992, and neither is what it’s hooked up to: a YM3812 “OPL2” FM synthesizer, a two-operator chip.

This is an interesting one because I think the YM3812 might be more nostalgic in the west, as it was used in the Ad Lib and Sound Blaster cards for the IBM PC, while the PC98 sound cards usually preferred four-operator synthesizer chips like the YM2608 “OPNA”. Here’s a clip of music from Mahjong Koi no Magic Potion’s attract mode. That twangy sound wouldn’t be out of place in a 1992 MS-DOS game! (Though either my capture or the sound filter circuit don’t sound great on those drums; probably my capture)

For sound effects, two of the Z84C011’s I/O ports are used as 8-bit outputs that can drive basic 8-bit DACs. This might takes up almost all of the CPU time, but that doesn’t really matter at all, because this is a dedicated sound CPU. The sound effects sound… fine. All of the sound samples and music data are contained in a single 128kiB ROM.

Video

Consider the technical requirements. Nichibutsu was making mahjong and hanafuda games. They had short shelf-lives, so they had to be as cheap as possible. Nichibutsu’s non-mahjong arcade business was in steep decline as they moved to consoles (for example, 1992’s Terra Cresta II was a PC Engine exclusive), so they didn’t reuse hardware from that. Card or tile games, on the other hand, don’t rely very much on needing to move a lot of objects around the screen. Having larger, detailed objects is more valuable.

So Nichibutsu went with the blitter. Amusingly, the main example of a 2D blitter-based arcade hardware on this blog has been the CAVE CV-1000, which was specifically made to move a lot of objects around on the screen to accommodate bullet hell shooters. But that’s what ten years will do for you; as well as a 133MHz SH-3 on the CAVE vs. our main CPU, a 6MHz Z80-with-stuff-duct-taped-to-it.

As a quick summary, blitter hardware generally works as follows: a dedicated area of RAM, the framebuffer, is used to directly render the screen. (The Nichibutsu system is paletted) This part is similar to other directly-addressable-pixel systems, like the Apple ][’s HIRES mode. The blitter, however, is dedicated hardware that can receive commands from the CPU, which will cause it to copy blocks of data directly into the framebuffer. It is optimized for the graphics usecase, which involves rows that may need to be shifted or with transparency.

I’m pretty sure these surface-mount NB9010 chips are associated with the frame-buffers, and the Koi no Magic Potion hardware features two of them. That means two framebuffers overlaid on each other; since these also have hardware scrolling registers, this can be used to have a single moving object, or just the usual use, two layers on top of each other. (Plus, you can do linescrolling effects, like in the title screen video above) The CAVE CV-1000 hardware doesn’t have this capability, and I’ve also not noticed slowdown in a Nichibutsu mahjong game. Clearly this is much more advanced.

The pixels on the Nichibutsu hardware are very much not square; in fact, at a 240p row being 640 pixels wide, they’re essentially halved horizontally. Color palettes are 12-bit RGB, which is nothing special in 1992, but good enough to show a pretty girl.

One thing worth noting is that the System11 blog has observed color fringing in some Nichibutsu mahjong games from 1989-1990 as a result of using 74LS-chips that are just a little too slow for the job. It looks like by 1992 they had fixed this, since I don’t see any equivalent here; it looks to me like this hardware was constantly being iterated on over time. As an aside, if you like strip mahjong hardware, check out the system11 blog.

Koi? No, Magic Potion!

So, what is Mahjong Koi no Magic Potion? The title means “Magic Potion of Love”, but I think that choice was made for a simple reason unrelated to the game. Specifically, it’s hard to ignore the popular 1991 song Koi no Magic Potion. (Or, uh “Koi no Magic Portion”. My Japanese is terrible I can’t talk…) Nichibutsu was definitely not above a few pop culture references to get attention in a crowded arcade, but I don’t think the game has very much to do with the song.

The doctor gives you the bad news in the attract mode: your disease is incurable. And maybe they could make a cure, but you won’t live long enough for them to develop it. But then on TV, you find out that a scientist has built a time machine… That’s the magic potion you’re looking for; thankfully, in the future we’ve decided that yes, we should put medical cures in big scientific potion flasks.

As for the stripping? (That’s what you’re all here for) We know that in 1992 Nichibutsu left JAMMA because they didn’t want to follow restrictions that resulted in Mitchell putting out a game that became known as “strip mahjong without stripping”. Mahjong Koi no Magic Potion, though, is honestly to my eyes less sexual than Mirage Youjuu Mahjongden. Yeah, there’s girls in their underwear, but they seem to be enjoying themselves throughout, which is what I think Mitchell’s game used for its edge. Also there’s no giant tongues. You don’t even get to see a nipple.

Gameplay

Mahjong Koi no Magic Potion is a mahjong game. You play a two-player variant of Japanese riichi mahjong. In fact, the gameplay is subtly simplified here. Notice that on screen, the girl’s face is huge, taking up a lot of the game. Like Mirage Youjuu Mahjongden, your opponent doesn’t have points, per se; instead, a love percentage ticks up. Once it reaches 100%, you win, which generally takes three rounds.

But you might notice something is missing: the opponent’s hand. You’ll only have the game scroll up to show you it if you lose. Now, they’re still discarding tiles, and you can call those tiles, but as far as I can tell, your opponent will never make a chii, pon, or kan call. That makes this mahjong engine less advanced than 1989’s Mahjong Daireikai. Your opponent will always have a closed hand, and usually will call riichi, though not always.

Mind you, the game is still good enough to know the rule of furiten, so don’t think you can play too lazily.

So, how do they beat you? Obviously, they just get massively favorable hands at a rate higher than would be expected from random chance. Also, check out something else there: mahjong fans will notice that 三連刻, sanrenkou, is not a common yaku in riichi mahjong. It’s a relatively rare local yaku, which my opponent wields regardless. I’m not sure if this was considered a standard yaku in 1992.

If you do manage to win a round against a girl, you get the obligatory stripping scenes. The game makes an effort to add some gameplay with quiz questions during the stripping scenes. These questions, like “which breast do I have a mole on”, “am I holding a pillow or a stuffed animal”, “what has baggins got in his pocketses”, etc. don’t seem to really be predictable in advance. They kind of remind me of the ZZT game Parell Wars 1, which came out seven years later and features a scene wherein you are asked a password at the bank and are given two options, with no clue to guess which is right.

Parell Wars 1, in true ZZT fashion, kills you if you get the question wrong; Mahjong Koi no Magic Potion just removes a few percent from your love meter. However, if you get too many wrong you’ll end up having to play one more round of mahjong against the same girl rather than getting to see her final picture or advance the plot.

Cheat items in Mahjong Koi no Magic Potion work similarly to Mahjong Daireikai in that you gain points for each han you score in a hand that you can spend on them. Unlike Daireikai, you can reuse the items; each use is what costs points, but you have the ability to choose whether or not to use an item right when you need to. For example, you’ll have the option to use an item that lets you see what the opponent’s riichi wait is when your opponent calls riichi.

Oddly, these items are given out or powered up over the course of the story, so you start out having to play regular mahjong, with only the additional option to switch out tiles you don’t want in your initial hand, a gift from the first girl in the game. (Something so common in video mahjong, “BET” games often give you it for free) I won’t give away too much here, but you do get access to the time machine, and get to go to the future. Thankfully, it’s pretty similar to the present. In fact, I suspect this image is a digitization on top of a photo of an actual place, though I’m not sure where.

Mahjong Koi no Magic Potion also features multiple endings, but I’m not quite sure how to trigger them. There are two full playthroughs of the game on YouTube, one gets the good ending, one gets the bad ending and I don’t know why. Maybe depending on how you treat the scientist? You do get to play against him, but he won’t strip.

Note that I do know which one is good or bad; Mahjong Koi no Magic Potion has a full suite of debug features accessed by dip switches, including an ending select.

Another fun thing in the debug mode is when you go into an option that requires which girl to look at, you’ll see two “JAMA GAL”. Who are these? Are they the incarnation of JAMMA in female form?

No. JAMA is a transcription of 邪魔, which just means “a bother”. These two girls are the incorrect option when you choose one of three girls in the future; you still play a round of mahjong with them, but they won’t strip. You do get smiley-face points for your han if you win, but you will also lose your credit if you lose, so they mostly just serve to lengthen the game and annoy you, and even Nichibutsu recognized that.

Drink the potion

First off, I’d like to thank the flyer for some beautiful close-up CRT pixels. Yep, people in the 90’s knew those looked good too, even when they were just the normal way to see pixels. Also they were easier than having additional art. Click on it for my full 1200dpi scan, 26MiB of CRT glory. Don’t you all do it, though, I pay for my own bandwidth. (Also I just noticed now my scanner cropped off the top, why did it do that, rude)

Mahjong Koi no Magic Potion is the most fun I’ve had with a strip mahjong game. However, the game is pretty much entirely forgotten; I couldn’t find any sources of any worth in Japanese. Which makes sense; as I noted, these games were made in bulk and swapped out fast. Would I call it a hidden gem? I mean, it’s still a strip mahjong game, whose mahjong engine is simple even by genre standards. But I guess the light-hearted plot and pleasant art swept me up.

All of Nichibutsu’s game rights now belong to Hamster Corporation, so I assume that includes Mahjong Koi no Magic Potion. Other mahjong series, like Jaleco’s Idol Janshi Suchie-Pai and Seta’s Super Real Mahjong, have gotten modern compilation re-releases, but nothing of the sort exists for Nichibutsu’s arcade-exclusive titles, and they’re obscure enough that I’d be surprised if that changes. So for now, MAME or this PCB are the best way to play them. Or just watch a video. There isn’t that much gameplay.