Season 1 · 12 episodes
On the first day of middle school, Nayu Hayama accidentally shows her black lace panties during the opening ceremony. Yako Jingūji and Haruka Shiraishi hear rumours of her doing "enjo-kosai" or prostitution, and spot her talking on the pho…
When wondering about which club to join, Yako gets a bit agitated when her mother is brought up. Whilst changing, Nayu spots Yako with a bra her mother brought, who gets riled up when Nayu tells her it is too soon for her to wear one. She …
One of the male students, Hiroki Komachi, tries to have a word with Nayu, but ends up getting occupied at every chance he gets. Nayu, Haruka and Yako take a look at the Crafts club, but leave when the club's adviser, Tsukamoto, shows disda…
Haruka feels down when the boys start teasing her for her big breasts, even ranking her #1 in a 'biggest breasts' chart. She and Yako visit Nayu's house, where Nayu asks them to be models for a fitting session to gain awareness for the und…
Nayu explains her situation to Keigo. Hiroki then comes over to Nayu's house to apologise and ask is there's anything he can do for her, inadvertedly offering to help her make an 'Underwear Appreciation Society'. Nayu also manages to convi…
After Kiyono joins the society, the girls become aware of her habit of teasing what's under her skirt in front of boys. She flips up Yako's skirt and makes fun of the underwear, only to show some embarrassment when she flips hers back. The…
Hiroki's newfound knowledge of underwear is affecting both his concentration and his reputation. Nayu gets a mysterious 'love' letter in her shoebox. Hiroki gets annoyed and decides to quit the underwear society. On his way home, he runs i…
Mizuno has a rather dubious dream about Keigo. The next day the Underwear Society go on an overnight trip to a beach hotel where Nayu's grandmother used to stay. Mizuno brings her old school swimsuit which the girl's accidentally wreck whi…
Yako gets annoyed when her childhood friend, Kota, who insulted her flat chest when she tried changing in front of him. Haruka feels some tightness in her chest, which Mizuno deducing that she is starting to develop feelings towards Hiroki…
Kiyono reveals she is going to be a model for her mother's underwear collection, but has a problem with her current breast size. Nayu and the others try to help make them bigger, but to no avail. She tries doing the shoot wearing a slightl…
As the Underwear Society make preparations for the drama club, they are asked to participate in the performance. After school, Nayu runs into Kiyono, who had heard about Keigo's job offer. The next day, Nayu takes on some extra work whilst…
Haruka feels betrayed by Nayu's announcement and stops being friends with her. That same night, Mizuno's apartment catches fire. These events leave everyone in a negative mood, and Nayu's texts to Haruka fall upon deaf ears. Later on, the …