That Mysterious Little Boy I met Under the Tree

3 years ago, Johannes Cleis found his little sister on the street. Bloody and lifeless. Swearing to find the murderer who killed her, he went to investigate the ones responsible for her death.

Fast forward to the present time, he made a mistake that got him chased by an unknown mafia group. That also led him to climb up a tree and accidentally fall, which cost him his memories.

After losing his memories, he met a mysterious young woman who saved his life... And mistook him as a little boy due to his small stature similar to a young kid.

However, because of his amnesia, he can only remember the events 16 years ago, which gave him the mind of an 8-year-old. Unbeknownst to him, he will be thrown into a life filled with doubts and secrecies.

Will he still be able to find the one who murdered his little sister? What will happen to him after meeting that mysterious woman?

And does his family keep something important from him?