Another ending where you drown！
...is what I thought, but it continued on for a little bit longer.br> Though in either case, it is a bad ending.

In order not to receive a bad ending, you need to pick the choice "Rouryuu is?" on Day 4, choice number 2.
You need to unlock Seal 2 in order for this choice to appear.
There's two way to accomplish. If you view the finals stage on the 5th day of either Yasumi or Nami's routes.