Here is some info about how he died and also some history of the band..
Information on the Raphael:
Raphael was formed in March 1997 and had to disband after the death of the leader, Kazuki on 31.10.2000 at 9a.m. Kazuki died from an over dosage of Tranquilizers. A medicine to reduce stress... Kazuki was the one who named the band, "Raphael", as he remembered "the healing angel" as raphael at his Catholic School. It was because Kazuki wanted his music to be able to heal the hearts of the listeners. Their major debut was in July 1999 with their single 'hana saku inochi aru kagiri'.
More information on Kazuki & the band:
Kazuki's story is a very sad one. He leaded a hard life at a young age. He's father had disapproved of Kazuki's dream of being a singer and putting all his efforts into music. And because of this, Kazuki ran away from home at the aged of 15. He was all alone at that time and aimed on pursuing his goal in life. But during this time, Kazuki met Mr. Hirai who soon became Raphael's producer. Mr. Hirai invited Kazuki to stay and he was willingly to help Kazuki work towards his goals. And because of Mr. Hirai, Kazuki was able to form Raphael with Yukito. Later, Hiro & Yuki joined the band.
All members of Raphael quitted school at a young age to pursue their dreams and goals in life.
As for Kazuki, he's dream was to become a great musician... and he's dream did came true...
Being the leader of Raphael at such a young age, Kazuki had to face lots of problems and had great responsibilities. Thus, Kazuki started to take Tranquilizers to relieve the stress he was feeling.
On top of being the leader of Raphael, he was also planning on his solo career which added stress too. That was how Kazuki sadly passed away unexpectedly.
A day before Kazuki's death, he and the other members of Raphael was having a handshake meeting with fans & he was jokingly playing with Yuki too... But, the next day, fans were shocked on hearing upon this news...