Sasami-san at Ganbaranai

The story follows a hikikomori (shut-in) named Sasami who is unmotivated about even changing clothes or eating. Her brother takes care of her, even though she despises his slave-like nature. Sasami spends her days viewing the outside world via a "Brother Surveillance Tool" on her computer. In the outside world, the three beautiful Yagami sisters and Sasami's brother are in the middle of relationships worthy of a romantic comedy. (Source: Anime News Network)

This takes place during Valentine’s Day, and although Sasami tries to make some chocolate herself, her brother does it for her in the end. Not sure if she can give him chocolate he made, she thinks of something else she can give him. - YQII