Zero In (ゼロイン?), also romanized as Zeroin, is a Japanese manga series released in 2004 by Sora Inoue, serialized in Monthly Dragon Age magazine and published in Japan by Kadokowa Comics Dragon Junior.
In the near future, the Japanese National Police Agency covertly establishes an armed division called Minkei or Private Police in order to stem out rampant crimes that has firearms involved by heavily armed criminals and terrorists.
- Kou Shiraishi
Kou Shiraishi is an average 16 year old high school student who is usually bullied. He is involved in a bank robbery and home assault, in which he meets Mikuru. Afterwards, he enrolls in the Minkei training program, where his team, thanks to his planning, is the only one to survive the final test. His position in Minkei is a "Keeper", who acts as support. His overall physical condition has improved since his training and is thought to have learned "Zero In", though there is no concrete evidence of him using it. He has a crush on Mikuru.
His family consists of a brother, a little sister, a mother and father. His brother is a police officer, his mother is a former police officer, and his father is a detective.
- Mikuru Nazume
Mikuru Nazume is a 16 year old member of Minkei, also known as "No-Murder Mikuru", due to the fact that she refuses to kill anyone. This comes from when she was little, when she was held hostage and forced to kill her own father after being drugged by the criminal who later killed himself. She is good with guns (Her mother is a gunsmith and customizes the guns) and un-armed combat and uses "Zero in: Burst" as her main technique. She seems to have fallen in love with Kou and gets jealous easily. She had a rivalry with Kina over Kou but in the end Kina gave up. She is also the the idol at her school.
- Kina Monjou
18 year old member of Minkei, she was partnered with Kou during the training program a few times. She had an attraction to him due to a habit they shared. Her grandfather was part of the yakuza and was killed along with everyone else in the household by the hitman, Black Dogg. She was hidden at the time and despises yakuza and hitmen. In combat she uses either guns, or a special sword that she's skilled enough with to cut a car in half. Along with Kou and Mikuru they finally captured Black Dogg, but she was shot in the stomach and spent some time in the hospital. Afterward she retired from Minkei and was planning to go back to her family's home, but while wearing only normal clothing and not carrying any weapons, she was shot and killed in by her stalker, who made it look like a mugging, in order to bring his dolls to "life". Ironically, one of Kina's favorite saying is "I'm immortal".
Her hobbies were cooking and she was on-par with Kou's sister. She gave Kou her treasure after hearing that he loves Mikuru.
- Shikie Misono
A Tokyo metropolitan officer, she kills all criminals rather than merely apprehend them. She uses needles to stun people. She hates people with "weak eyes" like Mikuru and even referred to how Kina died is similar to how a dog dies, she sees imprisonment as useless since criminals don't regret killing and from her fight with Mikuru, she seems to have experienced something similar to her. In chapter 20 this is confirmed, her partner was killed because she hesitated and was shot many times. She has multiple gunshot wounds on her back.
When Shiraishi protected her from gunmen after she was suffering from pain caused by her old wounds, his actions touched her to point of refraining from her killing habits. She also seems to have developed feelings for him as a result.
- Hana Tomozou
Fresh from the Minkei training academy, he's in the team two months after Kina's death. He like's to refer to himself as "Ross" and gives nicknames to others. He seems to be trigger happy but doesn't kill.He usually paired up with Shikie Misono and calling her "Russian".
- Fujita Nanami
13th division leader of Minkei, age 33. She's married and has a child. She's the most trusted member of the 13th division and is referred to as "Leader".
It`s been shown that she is a slob at home.
- Yuuji Hisamaki
The instructor at Minkei Training ground, he's tough but a knowledgeable trainer. He's a Zero-Master and was capable of seeing and blocking Mikuru's "Zero In: Burst", has an interest in Kou after seeing his improvement.
- Araki Kazutahito
A police officer who is constantly seen as the one enlisting Minkei's help to catch panty thieves (or other perverts), he takes credit when he does nothing and sees Mikuru and Kina as monsters (due to the excessive damage they cause) but he does show concern for them. In chapter 18 he leaves flowers at the place Kina was killed, saying how losing her was unbearable.
- Nomihara Noriko
A girl attending Kou's school, she's first seen in chapter 15, being robbed and after Kou saved her, she seems to have a crush on him.
- Command Zero
Also known as Zero In, is a technique used to cope with sudden attacks or indoor situations. It wasn't originally intended to be used as an attack but Mikuru's grandfather refined it. It's said that only 10 people in the world can master it.
- Burst - An attack using a pattern of blows, often used with guns in hand (hitting with the gunbarrels, not firing.)
- Fast Break - A quick Combination
- Pressure Decoy - Creates a decoy
- Buster - A single-shoulder ramming technique
- Yuuji Hisamaki
- Mikuru Nazume