Ayumu Mutoh (武藤 歩, Mutō Ayumu) is the 14-year old daughter of Koichiro Mutoh and Mari Mutoh, the older sister of Go Mutoh and a member of the track and field club who is expected to be Japan representative after four years.
Ayumu is a young girl with medium long brown hair and brown-golden eyes. She usually ties the top part of her hair. She's got a slim and sporty body and olive skin. She is half Japanese and half Filipino.
When the first earthquake started, Ayumu was in the track and field club practice at a stadium. Their coach then announced the members for the 400-meter relay race and appoints their ace Ayumu as the anchor. An earthquake hits Tokyo and the coach decides to end the practice.
At the girls locker room, a second much stronger and destructive earthquake hits Tokyo. When Ayumu opens her eyes, she sees some of the girls had died and a girl asking for help, but she panics and runs away. She heads home, but is unable to find Go there, so she goes to a nearby school yard where people had gathered, but is still unable to find any family member. She sees colorful lighting on a hill and that reminds her of what her father did to their house plans and heads there. Reaching the tome, where a shrine is, she sees her father Koichiro Mutoh, who also tells her he couldn't find Go. Nanami Miura then comes carrying Go Mutoh as he was injured. She is worried if his eyes are okay, and Koichiro removes his bandages to see that only his eyelids were cut and patches them. Their mother arrives next and they are glad that all are fine and take a picture. When the signal on their phones return, Nanami borrows Ayumu's phone to call her family and Ayumu recalls how she left her team when they needed help, but her family comforts her.
- The name Ayumu means "walk" (歩).
- Ayumu's surname Mutoh means "military, martial" (武) (mu) and "wisteria" (藤) (toh).