17.3 about a sex

When Kouichi arrives at his new school, he immediately senses something frightening in the atmosphere of his new class, something that no student wants to talk about and that seems to be related to a mysterious and silent girl.

A Happy alien, Takopi, lands on Earth with one mission: to spread happiness! When he meets Shizuka, a lonely fourth grader, he vows to bring back her smile using his magical Happy Gadgets. But as he uncovers the pain in her life, Takopi learns that true happiness may require more than gadgets.

Shy Natsu awakens as part of a group chosen to ensure the survival of humanity. Together, they have to survive on a changed Earth.

Kiyotaka Ayanokouji enrolls at the prestigious Tokyo Koudo Ikusei Academy, but is assigned to Class 1-D, where students with behavioral problems are housed. The school awards points equivalent to 100,000 yen per month and allows unusual freedom in classes, masking a more complex system.

Seventeen-year-old Mugi Awaya and Hanabi Yasuraoka appear to be the ideal couple. They are both pretty popular, and they seem to suit each other well. However, outsiders don't know of the secret they share. Both Mugi and Hanabi have hopeless crushes on someone else, and they are only dating each other to soothe their loneliness. Mugi is in love with Akane Minagawa, a young teacher who used to be his home tutor. Hanabi is also in love with a teacher, a young man who has been a family friend since she was little. In each other, they find a place where they can grieve for the ones they cannot have, and they share physical intimacy driven by loneliness. Will things stay like this for them forever?

Kotarou Azumi and Akane Mizuno became third year students at junior high school and are classmates for the first time. These two, along with fellow classmates, Chinatsu Nishio and Takumi Hira, relate to their peers through mutual understandings and feelings. As their final year at junior high school progresses, the group overcome their challenges to mature and become aware of changes in themselves.