Secret Tsubomi) is a Japanese slice of life romance shōjo manga series authored by Yū Yabūchi, and published by Shogakukan.

[2] Sentai Filmworks released the OVA in North America in January 2018.

[5][1] Naisho no Tsubomi tells the story of Tsubomi Tachibana, a fifth grader dealing with rather sensitive issues such as her mother's pregnancy, her first period and the strange feelings she has started to get when around boys.

Each volume tells the story of a different girl, always with the given name of Tsubomi and similar appearance.

In each case the story deals with various issues the girl experiences with early adolescence, including physical matters such as menstruation and breast development, personal issues such as the first crush, and more uncommon but dangerous issues such as the risk of predation (this was not included in the anime).