Piranin

Piranin (Japanese: ピラニン Piranin) is one of the students of Midnight Horror School. During the daytime, he is a long-forgotten legend of a sea monster.

Appearance
Piranin has a head resembling some sort of fish (likely a piranha, as his namesake appears to be) or aquatic monster, with green fins on the sides and top of his head. He has pointy teeth, blue eyes, and stitched-up eyebrows. The stripes on his shirt are yellow and blue, with a white P decorating the middle.

Personality
Piranin is shy, quiet, and a bit of a pessimist at times. He doesn't have the most confidence in himself, which is sometimes used as a plot point in episodes like ''Dash! Desk Race or Piranin The Beast''. Despite this though, he's very friendly with many of his classmates, most notably with Hikky, Liddy, and Spimon.

Wonder
In the episode Piranin The Beast, Piranin, inspired by one of the school's previous graduates Nessie, tries to become a terrifying sea monster, believing that is most likely what his wonder must be. After a plan organized by Hikky, Liddy, and Spimon to turn him into a sea monster seemingly worked, the school's principle gave him permission to graduate. However, after being informed he'd have to live alone the rest of his life by graduating, Piranin decides he doesn't want to go.

Trivia

 * Tubee and Piranin are the only characters to make a physical appearance in every episode, though Tubee has far more speaking roles than Piranin.