In the early morning hours of April 16, Ryunosuke Seki, 22, and Masataka Iino, 32, both of whom are members of the Matsuba-kai, are alleged to have beaten the head and abdomen of Yusuke Kawashima on a road. The victim subsequently died.
The following day, Seki learned that Kawashima had succumbed to his injuries by a reading a newspaper article. The gang member then turned himself over to police.
Both suspects have been charged with manslaughter. Neither suspect has commented on the allegations, according to police.
Kawashima is known to have visited a restaurant managed by Iino. Police are now investigating whether the visit to the restaurant is connected to the incident.