Public prosecutors indicted the president of a tour boat operator on Wednesday over a fatal sinking incident off the Shiretoko Peninsula in Hokkaido in April 2022.

The Kushiro District Public Prosecutor's Office charged Seiichi Katsurada, 61, head of Shiretoko Yuransen, based in the Hokkaido town of Shari, with professional negligence resulting in death.

Katsurada has denied the charges, according to investigators.

The Japan Coast Guard arrested him last month over the loss of all 26 people aboard the sunken Kazu I tour boat.

It alleged he neglected his duty as the person in charge of the Kazu I's operation to give appropriate instructions to the boat captain, resulting in seawater gushing in through a hatch due to high waves, causing the boat to sink.

On the day of the incident, Katsurada let the Kazu I operate after deciding with the captain that the boat would return if the weather worsened.

He is believed to have told investigators after his arrest that the sinking could have been avoided had the captain turned back.

Katsurada's trial is expected to focus on whether the accident was foreseeable.

The sinking occurred near a waterfall in the peninsula on April 23, 2022.

The Kazu I left port at around 10 a.m., and contact was lost at around 1:26 p.m. after a passenger called a relative.

A total of 20 passengers and crew were confirmed dead, while the remaining six are listed as missing.