Naisho no Tsubomi

Each volume features a different protagonist, all named Tsubomi but with distinct surnames and individual stories. The first volume follows a fifth-grade girl navigating early adolescence, including her mother's pregnancy, her first menstruation, and new emotions around boys. The second volume introduces another Tsubomi, also a fifth grader, who meets an alien chosen to study Earth and selected her as his subject. The remaining volumes follow additional Tsubomi characters, each with their own surname but no further details provided. The series received the 2009 Shogakukan Manga Award in the children's category.