Quote from Cucurbita;249928:
What rank system?
There exists a rank system in this game. As rank increases, enemy bullets will generally become faster and more plentiful. This effect that rank has in this game is most prominent with boss attacks, where the bullet count difference between minimum and maximum rank can differ by a factor of 4 or more, and bullet movement speeds can double. Note that the game does not display the numerical value of rank at any point - under most circumstances, it can be estimated only by observing bullet pattern behaviour.
Rank ranges from zero to thirty-two, and is reset to sixteen at the beginning of each stage. It increases gradually with survival time, and jumps up noticeably on defeating spell cards, until it reaches the cap of thirty-two, corresponding to the highest variable difficulty. The rank value is decreased by sixteen whenever the player is hit. This means that, for the most part, the only way to reduce the variable difficulty is to die. Since the rank drop occurs on a hit, not a death, it is theoretically possible, through counter-bombing (see Lives, above), to reduce the value by sixteen without the loss of a life. Since the game's allowed counter-bomb interval is so short, though, it is difficult in practice to do so deliberately.