He killed his younger twin brother, Tsukasa Yugi, and died young. Hanako is the only known person to ever have altered his fate. By inflicting himself with the Mermaid's Curse, he bound his and Yashiro's souls together.

What age did Hanako Kun die?

1 He Is Chronologically 50+ Years Old

It is unknown exactly when Hanako died, but by the period we see in flashbacks, he probably attended Kamome Academy fifty years ago.

Why did Hanako Kun kill Tsukasa?

It was all because he was curious. Hanako is not afraid that his brother will come for revenge. Hanako is terrified that someone might find out that he killed his brother. He loves his brother as much as Tsukasa loves him.