Full Name: Mika Koizumi
Ranger Designation: Yellow Four
Weapon : Thunder Sword
Mecha : Bio Jet 2
Vehicle : Bio Machine 2
Age: 18
Abilities: Action Shooting, Strobe Flash, and Chodenshi (Super Electron) Holograph

Mika was originally a photographer who was hesitant at first to join Bioman. She was the more hard driven female of the two. In fact, she was the first female yellow ranger.
Actress: Yuki Yajima (had a role in Sharivan)

Suit actor: Hirotsugu Tsuuji (also plays Ju-Oh in Bioman)