School: Gehenna Academy Club: Problem Solver 68 (Position: President) Year: 2nd Year Age: 16 Birthday: March 12 Height: 160cm Hobbies: Studying business management Signature Weapon: Sniper Rifle "Wine Red Admire." Modeled after the PSG-1. Though it is quite heavy to handle with one hand, Aru is capable of firing it one-handed. A second-year student at Gehenna Academy and the President who leads the club (organization) "Problem Solver 68." She always wears a fearless smile, maintains a mature, lady-like manner of speech and behavior, and toys with those around her with a suggestive attitude. In appearance, she is the very image of an "evil charisma." ...Or so she pretends, but in reality, she is a gullible klutz.

School: Gehenna Academy Club: Problem Solver 68 (Position: Section Manager) Year: 3rd Year Age: 18 Birthday: March 17 Height: 157cm Hobbies: Collecting music CDs Signature Weapon: Handgun "Demon's Roar." Modeled after the H&K P30. Since it emits a considerable roar every time it is fired if used as-is, she has equipped it with a silencer. The voice of reason within Problem Solver 68 and a long-suffering soul surrounded by troublemakers. She ended up joining the group after being swept along by the flow, and to top it off, she was made Section Manager. Although she often sighs at Aru's impulsive actions, she does value Aru's character deep down. She loves heavy metal and collects CDs of hard music; the skull-like symbol on her hoodie belongs to her favorite music group, "Black Death Poison."

School: Gehenna Academy Club: Problem Solver 68 (Position: Chief) Year: 2nd Year Age: 16 Birthday: July 29 Height: 144cm Hobbies: Collecting bombs Signature Weapon: Machine Gun "Trick or Trick." Modeled after the MG5. She also possesses various bombs, which she keeps packed tightly inside her favorite bag. A major prankster and a childhood friend of the President, Aru. She understands Aru's vanity and bluffs—her desire to act like a cool outlaw—better than anyone else in Problem Solver 68. However, she shows no consideration for that. Rather, she understands it and uses it to tease her, seemingly even enjoying the chaos that ensues.

School: Gehenna Academy Club: Problem Solver 68 (Position: Rank-and-File Employee) Year: 1st Year Age: 15 Birthday: May 13 Height: 157cm Hobbies: Growing weeds Signature Weapon: Shotgun "Blow Away." Modeled after the HK FABARM FP6. It is apparently used for Haruka's "pest control," though the definition of that seems to vary by time and occasion. She also appears to use it as a blunt weapon during combat. Negative and always timid, she refers to her comrades (or rather, her superiors) by their titles, likely due to her position as a rank-and-file employee. She looks up to Aru, calling her "Aru-sama," and has an incredibly strong desire to be useful to her. However, her intense feelings often lead her to go out of control.