Naisho no Tsubomi

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. When she first met Daiki, she tends to blush a lot when she is around him, she does not know what that feeling is at first, but further into the story she then discovers that she, in fact, has fallen in love with Daiki.

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). Each story also includes some source of candid advice and information to support the girl, such as the spirit of a future sibling (volume 1), an alien posing as a twin brother (volume 2), or even another self from a parallel universe (volume 5).

Tsubomi Tachibana (立花 つぼみ, Tachibana Tsubomi)

A fifth grader who deals with sensitive issues while growing up. She is worried about the people around her and tries hard to help them when they are in need. This leads to her trying to handle issues such as her first menstruation alone. Although Tsubomi is a responsible and helpful girl, she is naive in a sense that she does not understand many things around her. She is happy about her mother's pregnancy, as she is an only child and has always wanted a sibling.

She is troubled about lot of things like the strange feelings that she has around Nemoto, the "indecent things" that her parents have done to make a baby, and her feelings towards Saya when she gets close to Nemoto. Tsubomi is shown to have feelings for Nemoto but does not quite know it herself at first. She later confesses to Nemoto, and the two become a couple.

Voiced by: Kaori Nazuka

Saya Endo (遠藤 沙耶, Endou Saya)

A beautiful new transfer student in Tsubomi's school and class. She knows many things and is a friendly character. She gets along with Tsubomi from the beginning of the story and acts like a sister to her by helping her with her problems. Not only she helps Tsubomi, she even helps Daiki. She seems more mature than other children of the same age.

Voiced by: Ami Koshimizu

Daiki Nemoto (根本 大樹, Nemoto Daiki)

He is friend of Futoshi and You. He calms Tsubomi down when she is going to see her mother and gives her a toy duck which she to attaches to her bag. He is nice and popular with girls, including those who are older than himself. He starts to have feelings for Tsubomi, and realizes them after they secretly see Yae and Yō kissing. Later in the series, Tsubomi confesses to Nemoto. He returns those feelings with his own, and the two become a couple.

Voiced by: Ryoko Shiraishi

Yae Yamabuki (山吹 八重, Yamabuki Yae)

Nicknamed "Yae-chin by her two best friends, Yamabuki Yae is tall, slim and calm. She is one of Tsubomi's best friends along with Rea-Pi. She is troubled by buying bras and her flat chest. She likes Saegusa and starts going out with him in chapter 5, and they kiss in chapter 9.

Voiced by: Sanae Kobayashi

Rea Katō (加藤 麗愛, Katou Rea)

She is small, hyperactive and very curious, mostly about perverted things. She is one of Tsubomi's best friends, along with Yae-chin, and Futoshi's childhood friend. She is teased by Futoshi about her body and weight frequently, which makes her want to be slim and beautiful, as her current body shape appears to be curvier than she would like. Her friend's nickname for her is "Rea-Pi".

Voiced by: Akemi Kanda

Yō Saegusa (三枝 葉, Saegusa You)

He is quiet, very popular and considered "the class idol". He has an older sister that helps Yae with her problems. He likes Yae and becomes her boyfriend in chapter 5, but they keep it a secret because many girls would be jealous.

Voiced by: Mitsuki Saiga

Futoshi Kuki (久木 太, Kuki Futoshi)

He is Yō and Daiki's friend, as well as Rae's childhood friend. He is perverted and often talks about big breasts. He takes apparent pleasure out of teasing Rea about her body shape and weight, though he actually likes her.

Voiced by: Kōki Miyata

On manga-news.com, the staff gave it a grade of 14.63 out of 20.[2]

• Naisho no Tsubomi (manga) at Anime News Network's encyclopedia