Sakura is an Idiot Heroine and as such a strong Power Nullifier; she can also suck out a person's life and if her blood ever interacts with powerful flame-manipulator Ogami's it creates a huge explosion (for their relationship's sake let's hope it's just their blood...
Yuuki is a Cloudcuckoolander and also one of the wealthiest people in Japan, one of the strongest super power-users (sound manipulation), and is EDEN's ultimate artificial being — his (more) super-powered side has no drawbacks like evil or Unstoppable Rage.
Toki is a Handsome Lech and the only one with a super power that can reach the evil power-nullifiers: metal manipulation. Super powers can't touch them but an iron bar to the head can... at least in theory.
Nenene is also somewhat cuckoo but that's just her de-powered side: her real personality is an ice-cold killer. Her powers are (or were) so strong that she gave half of them to her brother Toki.
Mitsuru is a very shy Hikikomori because her super-powered evil side can slice through people like a hot knife through butter. She has a lot of cats (a tiger is a cat, right?), is so beautiful despite not bathing or wearing clean clothes that her "fan club" made her (essentially) homecoming queen regardless of the fact that she never goes to class (she hides in an abandoned room) and she wields a flame that can burn the sin of lust that only Ogami is supposed to be able to use.
"The President" is a weirdo in a mascot suit and also one of the legendary Four Founders of EDEN, the good guys' Trickster Mentor, principal of Sakura and Ogami's school, a power-nullifier who infused the building with his own blood to protect it from evil power-users, and Sakura's biological father.
Zed is so Brilliant, but Lazy that he's normally dead: his power is life manipulation and he can make anyone an immortal "zombie". He's been carrying around the "lives" of three evil power-nullifiers for almost a decade, which doesn't sound like much until he puts one each in three of the good guys and they instantly de-power — Zed's only alive when he's de-powered and he's had those power-sucking orbs in his chest for years. No wonder he's one of the Four Founders of EDEN.
"Fussy Lunch" is, well, obsessed with lunch and leader of the other four (now three) evil power-nullifiers. His weapon of choice is a pair of chopsticks; the incredible amount of damage he does with them has nothing to do with his powers, he's just that freaking strong.