I guys, I'm playing Key of Heaven and I think it's one of the best action-RPG on PSP. I found out that there is a sequel (rather a prequel) called Tenchi no Mon 2. Unfortunately it never came out from Japan and China, so it is almost impossible to play without knowing Japanese or Chinese.
Is a...
@Xdqwerty, Osu! Tatakae! Ouendan! is the Japanese version of the game, different settings/characters/songs but otherwise identical mechanics. I played that before I knew about Elite Beat Agents lol. Both fantastic games https://en.wikipedia.org/wiki/Osu!_Tatakae!_Ouendan