Kasuga enjoyed reading in the library.
The book she is reading is about the human body.
Kasuga’s curiosity about male genitalia is still strong.
She turns pages, remembering her experience with Kobayashi.
She was a little disappointed because there was no picture of an erected male genitalia there.
When she sees a page, she is surprised at Kasuga and feels that the scales fall from her eyes.
She knew that her experience of putting a male genital in the hole of her female genital with Kobayashi was sex.
In the rain, Kasuga returns with Kobayashi with a single umbrella, and Kobayashi thinks Kasuga, who has few words, is strange, and Kasuga confesses to Kobayashi that it was sex during this time.
She’s incredibly surprised Kobayashi, and she says Kasuga to stop doing that.
However, she wanted to have sex in Kasuga and she started crying.