Each volume depicts a different heroine.

Vol. 01 tells the story of Tsubomi Tachibana, a fifth grader dealing with issues such as her mother's pregnancy, her first period, and the strange feelings she has started to get when she has been around boys.

Vol. 02 tells the story of Tsubomi Kusakabe, a fifth grader, who encounters an alien wanting to do research of earth. It turns out he has picked Tsubomi to be his research subject.

Vol. 03: Shiina Tsubomi (椎名つぼみ)

Vol. 04: Katanashi Tsubomi (小鳥遊 つぼみ)

Vol. 05: Aizaki Tsubomi (相崎 つぼみ)

Vol. 06: Nike Tsubomi (仁家 つぼみ)

Vol. 07: Yagi Tsubomi (八木 つぼみ)

Vol. 08: Honda Tsubomi (本田 つぼみ)

Note: Won the Shogakukan Manga Award for children's manga in 2009.