A former classmate I hated I became a naughty older brother Hirose, the heir of a large company, joins a cosmetics company mid-career because he wants to compete with his abilities. However, his ambitions were in vain, and he was living a smoldering life. Meanwhile, he meets Adachi, his high school classmate and club clubmate, at work. Adachi was appointed vice president of a construction company at a young age and was highly trusted by his subordinates. He was still the perfect man. Hirose has hated Adachi for a long time. Now that he has become a business partner, Hirose wants to somehow gain traction, but... “Why is this guy so sick!?” On the verge of falling into the best anime!!!