Ai-chan (アイちゃん, Ai-chan) is a recurring character in the Getsuyoubi no Tawawa illustration series. She is a high-school student who is famous among the boys at school. However, one random encounter with a salaryman eventually begins a story of teasing and popped buttons.
Ai-chan is a high school girl standing at 150 cm and weighing 50 kg. She has brown hair which she styles in a bobcut, but keeps two strands of her hair in braids which she keeps behind her ears. When not wearing her school uniform, she is often seen wearing a sweater and pants at home. During her middle school days as a class representative, Ai-chan has much longer hair, and arranges them into two ponytails on either side. She also wore glasses back then, and currently wears them only at home.
The Salaryman has commented that Ai-chan's looks would be appropriate to describe "youth taking a corporeal form", and Volley-bu-chan has seen how Ai-chan has taken the interest of the boys at school while incurring the jealous comments of the girls.
Despite her looks, Ai-chan has struggled with making friends at school. Because of the impressions people make of her, she tends to spend time in the classroom reading a book if she's not busy turning down a confession. However, she has showed a playful, almost mischievous personality when with people she is comfortable with, and is capable of showing a wide range of emotions as a typical girl her age. She also has a complex towards her figure, noticing that her bust size keeps on growing over time while staying at her current height.
- Ai-chan's name is a play on her bust size (cup size I) when she was first introduced. In later illustrations, she would eventually reach the cup sizes of J and possibly K. As of the latest illustration, her bust measurement is currently at 100 cm.
- Rumors from the girls at high school speculated that she already had a cup size of F during 5th grade of elementary school.