Why I'm in love now?

I don't know...

Tom thinks love is boring and meaningless, unlike his more emotionally mature twin brother Bill, who already has a girlfriend. Feeling insecure and not wanting to lose to his brother, Tom dates girls for shallow reasons and cheats, trying to fill an emptiness inside him, but those relationships always end badly.

One day, a new family moves in next door, and Tom notices a gentle, innocent girl. After meeting her, he begins to feel a warm, unfamiliar emotion. As he continues to see her every day, Tom slowly changes—he stops chasing other girls, becomes calmer, and finds his emptiness gradually filled by a quiet, sincere warmth, learning what genuine affection feels like for the first time.

''What is this feeling?''