18+ Senran Kagura: Senshi Bankou no Haruka

At Snake Girls' Academy, Haruka is vaguely thinking about graduation. One day, hoping to keep a record of cherished memories, Haruka begins to make a secret ninja tool in the laboratory. That is a "hanamenran" (camera).

Using the tool, when you take a picture of a person's smile, flowers bloom around the subject according to the smile. Sometimes, these instances of honest, natural interactions reveal new sides...

(Source: Kadokawa, translated)