In the music minigame Rudymical, the Boing Boing bombs that Kuito throws can be slashed twice in quick succession at correct rhythm, about two frames apart. Managing to do so will give credit for both slashes, increasing the combo count by two. This makes it absurdly easy to get 4-star performances, even on Difficult. There are two caveats to this, though.
1. If there are bombs in quick succession, it is near-certain that you will miss some of them, and it is hard to get back into the right rhythm during that phrase.
2. At the end of the song, the game checks if the max combo is EQUAL to the note count, among other checks. Doing this guarantees that you can NOT get the Full Combo bonus for that playthrough.
Play as Sola
Complete the game once to unlock the ability to play as Sola.
Secret Syega Shop Menu
In the Syega Shop Press L, R, L. R, L, L, R, R, X to reveal some hidden upgrades