Linn Suzuki (nicknamed Kotetsu by Miho Kuon) is the main protagonist to the series. She trains at the Kyo Hatchi school of martial arts to prove herself to Oni Azami. However, Oni treats Linn very badly causing Linn to run away to Tokyo in search of her missing brother, Tetsujin.

Linn's weapon is the katana, sakabatou a reverse-bladed sword which means that it has the sharp edge on the inside of the blade. The sword is said to have been forged on a demon's anvil for the legendary warrior Minamoto Yoshitsune. It is even said that the sword itself is possessed by a demon. Linn stole the sword from Oni when she ran away.

Linn is not very mature, and still seems to have the mind of a child. She is easily excited about anything and everything, panics when she thinks about sex, and tends to be annoyingly perky and care-free at times. In contrast, her speech pattern is quite formal and old-fashioned, due mostly to the fact that she was raised deep within the backwoods of old Kyoto. Despite her childish mannerisms, when forced into combat, Linn is a calm, controlled, and a deadly opponent.

Linn refuses to admit that she has any interest in Tatsuya, and can't really handle it at all when Miho teases her about him.