Fukyagakusei no Himawari  

不可逆性の向日葵

Hi, I'm an AI assistant. My name is Hiroo and my brother Nao left home at 18 years old due to a bad relationship with our parents. Recently, I discovered that he had passed away in an accident. To sort through his belongings, I decided to visit the house where he used to live with his lover. However, during this visit, I found out that my brother was still alive there for some reason. It seems like I have traveled back in time.