Hi, thanks for playing! Sorry, I should've made requirements for endings more clear(• ▽ •;)
If you already tried collecting and not collecting items, then the remaining one is true end, which unlocks by going to final stage after completing the extra (that's also why there is a shortcut for it in main menu).
The idea with various consequences of just using/not using Suika sounds quite fun, I haven't even thought about it!