|School||Kunugigaoka Junior High|
Kokona is Megu Kataoka's former classmate. She essentially blackmails Megu to do help her study after Kokona nearly drowned from failing to learn how to swim.
She has dark hair and dark eyes. She puts her wavy hair into pigtails with some pearls at the hair tie.
Kokona is very selfish and doesn't think about anyone else except for herself. She seems light headed since she went swimming in the sea after only practicing once with Megu. Because she isn't good at studying by herself, she blackmails Megu to help her study.
After Megu's practising, she gets a text message from Kokona, saying she wants to meet her again to help her study for exams. Korosensei, Nagisa and Kaede follow Megu to a café and find out that Megu is being blackmailed by her old classmate. Megu explains how she taught Kokona how to swim, due to her wanting to go to the beach, but she was so confident of herself, that she kept making excuses for ditching her practising lessons. When she was in the sea, she nearly drowned and blaimed Megu, saying how she is the reason she almost died. That's why Megu helps her with her studies. After realizing that it can't go on like this, Korosensei and the others decide to help Megu by teaching Kokona how to swim, making it seem like a dream for her. But the plan worked and Kokona gets way better at swimming, but Megu catches her and says how she doesn't need Megu's help anymore.
Megu and Kokona used to be friends because they were in the same class in middle school. One day Kokona asks her if she could teach her how to swim to impress a guy at the beach. She failed at learning how to swim because of her selfishness and her excuses and starts using Megu just as a tool. After Megu caught Kokona swimming fearlessly, they stopped meeting.
- Kokona Tagawa omitted in the anime.
- Her last appearance is in Chapter 118, eating together with Kaho Tsuchiya at Class E's restaurant.
- She had a traumatic fear of water, swimming and the sea.