unknown

As he is the same age as Shion he was presumably born in 2001. (Age 16) O 178 cm (5'10") 63 kg

A fugitive who is on the run from the police after escaping from prison. He sneaks into Shion's house after being shot. Nezumi gets treated and sheltered by him for a night, then disappears without a trace in the morning.

He hates No.6 and appears to know something about the city that no one seems to know.

He has dark blue hair and wears it in a short, but visible ponytail, leaving his fringe and strands of hair hanging at the sides of his face. His eyes are a light grey. In episode 2 of the anime, he wears a cloak with a hood (made of superfiber) which he soon took off to cover the enemy's eyes temporarily before holding a knife to his chin. He also used it to cover Shion and himself when they jumped out of a car(also in episode 2). He noted that he is taller than Shion, to which Shion agrees due to it being a valid fact. He wears grey pants (he tucks in the left side into a boot and the other is left as is and appears tattered), a dark green jacket with multiple pockets and a notably big scarf around his neck. He has a fairly muscular body.

When he was 12 years old, his hair was slightly shorter than when he turned 16 and he left it down. He wore a gray over-sized shirt with a wide collar and a pair of dark gray shorts. His weight was 37.1 kg and his height was 145.3 cm.

Nezumi is a rude and straightforward person. He has a deep hatred towards No. 6. Though deemed a criminal in the beginning, he seems to be an honorable person

(Source: No.6 Wikia)