I was curious about the effect of regional differences on speedruns for this game. This is a possibly incomplete list that could affect times, please add if I've missed any.

From the perspective of the international release:

• [slower] Scene 5-2, Maruyama has 8HP but only 4HP in the Japanese version.
• [likely slower] Scene 5-2, Maruyama attacks randomly but in the Japanese version has a predictable pattern: can attack once after three tower cuts.
• [faster] Scene 6-1, the claw picking up the battleship moves twice as fast in the international release.
• [faster] Scene 6-4, the power ups are grouped together but in the Japanese version appear one after the other.
• [slower] Scene 7-1, Nasty Gatekeeper has roughly double the health.
• [faster] Scene 8-5, Twin Freaks has roughly half health (but also has a smaller hitbox).
• [slower] Scene 9-3, Dark Demon has roughly double the health.
• [faster] No dialogue boxes before boss battles.

Is there an argument to separate the any% category into the different versions, or do the differences roughly cancel to being negligible?

First, I'll add:

• [slower] Scene 3-1, the Japanese version has a Headcase with Hammer Head at the Flying Soldiers battle.
• [faster] Scene 3-3, Japanese version has a slight delay before the arrow appears. (Edit)
• [faster] Scene 6-1, there's a second wave of Hovers and a longer pause before and after they appear.

Now let me break down those differences in terms of times based off of my splits, favoring the international version. Scene 3-1: [+7s] Scene 3-3: [-3.5s] (Edit) Scene 5-2: Japanese version will always be 110 seconds. International version is, of course, all over the place. My average time is 150 seconds; my best time is 70 seconds and I think mecharichter got 60 seconds once. But basically, [+40s]. Scene 6-1: [-30s] always Scene 6-4: [-20s] or less (don't have the intro in isolation atm). Scene 7-1: At minimum, [+10s] with a perfect bomb strat. Scene 8-5: [-30s] or less, never optimized this fight. Scene 9-3: [+45] or more Dialogue boxes: [0s] with frame-perfect clears, realistically more like [-5s]?

If we don't count a good 5-2 as likely, then with optimal gameplay, comparing the two versions, the international comes out about [13.5 seconds behind] (Edit). And yet a good 5-2 can set it [23 to 33 seconds ahead].

That's not a negligible difference either way. With that variability on top of its significant difficulty increase over the Japanese version, there's certainly enough reason to separate any%. Separate categories might even encourage more people to do speedruns! Maybe?

¤ clears throat ¤

Henceforth any% shall be separated between international and Japanese versions.