I search "NPC" in save data and luckily i find NPC ID. I try to edit some data and its work to make artist and solomon as my allies. This is the value:
Search for:
54 54 4C 4E 50 43 46 6C 61 67 53 74 61 74 65 00 00 24 00 00 00 54 54 4C 4E 50 43 46 6C 61 67 53 74 61 74 65 3A 3A 54 54 4C 4E 50 43...
@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