Gaku, who struggles with social interactions, has a world that revolves entirely around his best friend of ten years, Shouhei.
Kind and adorable—Shouhei belongs to him alone. As Gaku’s possessiveness grows, he starts wanting to monopolize Shouhei even more.
One day, he accidentally walks in on Shouhei pleasuring himself.
When he hears Shouhei moaning his name in pleasure, confusion floods Gaku’s mind—along with a single thought: "If we become lovers, I can have Shouhei all to myself."
Seizing the opportunity, Gaku suggests, "Let's date." Taking advantage of Shouhei’s feelings. But Shouhei rejects him, dismissing it as mere curiosity—!
"—If we're just friends, then why can you do things with me that friends don’t?"

Source: Shu-cream (Translated)
Note: Contains one extra chapter)