Iroha Miyamoto 巳屋本いろは

Although Iroha is only 15 years old, she's a powerful fighter and the first assassin (along with Hanzo) who tries to kill Koushi. But instead of killing him, she falls in love with him and decides to visit the same school as he does in order to get to know him better. Iroha has always been a mysterious and quiet girl before she met Koushi and Momoko, but after doing so she started to behave more like a girl in her age usually would.