Onii-chan Lab.

Ikezawa Sumire has three older brothers—Asagi, Ai, and Kon—who are so attractive that their friends often express jealousy. Sumire is fond of Asagi and Ai but feels indifferent toward Kon, though the reason remains unclear. The story focuses on the cheerful and lighthearted daily life within the family, highlighting the interactions between the three brothers and their younger sister at home.