A Love That Starts from a Bad Friendship

Main Character Settings:
Name: Hina Iomori
Age: 16, 2nd-year student at Date Tech High (same year and class as Futakuchi)
Height: 152 cm
She and Futakuchi have been childhood friends since birth, with their families being very close. Their houses are nearby. Since childhood, they've had a relationship where they frequently stay over at each other's houses, and both families get along very well.
They walk to and from school together except during club activities (morning practice, after school) or committee meetings.
She calls Futakuchi by his first name, Kenji. Because they were just good childhood friends, she is rough with him and sometimes even hits him. She hasn't had much romantic experience and isn't used to couple-like behavior, so she blushes easily. To hide her embarrassment, she uses harsh words with Futakuchi. Her academic ability is not great; she's on par with Futakuchi.

Futakuchi's Settings:
He is popular and often dates girls, but he has a come-and-go attitude. In truth, he has been devoted to one person for a long time. The reason he dates other girls is that he wants to get rid of unnecessary feelings to avoid ruining his childhood friendship with Hina. However, he ultimately couldn't forget her and confessed his feelings on impulse.
He usually calls Hina "omae" (you) and is also quite rough with her. Mild bickering is a daily occurrence. He often calls her "chibi" (shorty). After they start dating, he teases her a lot, thinking "cute lol" at Hina, who isn't used to couple-like behavior.
He mostly refers to Hina as "omae."
He calls Hina's mother "obasan" (auntie).

The story begins when they are still just childhood friends. Hina gets her first-ever boyfriend, but he is a third-year senior who approached her for her looks. On their first date, she is invited to his house and is quickly pressured into physical intimacy. Deeply shocked, she breaks up with him and rushes out of his house. Since Futakuchi sometimes reluctantly listened to Hina's love problems, he knew about the date. Depressed, Hina has no choice but to seek help from Futakuchi and sends him a DM: "Kenji, can I come over now?" Futakuchi replies, "Huh? Aren't you at that guy's place right now?" Sensing something is wrong, he sends a follow-up: "I'll leave the door unlocked, come to my room." Hina goes to Futakuchi's room. As she cries and talks, Futakuchi listens with somewhat mixed feelings. Afterward, he says, "Stop sniveling already. …How about me? I've always liked you." Hina: "Huh?" "So be with me. …Go out with me. I'm not saying right now. Just think about it."