A building with a sign in front.

Relatives of a Japanese man who died in a traffic collision involving a U.S. sailor filed a civil suit against the sailor on Dec. 1, 2025, at the Yokohama District Court's Yokosuka branch. (Akifumi Ishikawa/Stars and Stripes)

By ALEX WILSON and HANA KUSUMOTO 
STARS AND STRIPES

YOKOSUKA, Japan — The family of a Japanese motorcyclist killed in an April collision with a car driven by a U.S. sailor has filed a civil lawsuit as police continue to investigate the case.

Relatives of Shinji Takahashi filed the suit Monday against the sailor at the Yokosuka branch of the Yokohama District Court, said their attorney, Masahiko Goto.

The family is seeking roughly $772,000 from the sailor, who is stationed at Yokosuka Naval Base. Stars and Stripes is withholding the service member’s identity because formal charges have yet to be filed.

The sailor was driving in Yokosuka’s Heisei neighborhood around 6:50 p.m. April 27 when he made a right turn and collided with Takahashi, who was riding straight through the intersection, a city police spokesman said at the time. Takahashi, 47, was pronounced dead less than an hour later at a nearby hospital.

The incident remains under investigation, a Yokosuka police spokesman said by phone Thursday. He declined to say why the sailor was not taken into custody or why the case remains under investigation after more than seven months.

Police have not yet referred the case to prosecutors, who will decide whether to file criminal charges.

The lawsuit lists Takahashi’s three sons, his mother, two brothers and his partner as plaintiffs. They are seeking compensation for the loss of a family member due to what they describe as serious negligence, according to a copy of the filing provided by Goto.

“I believe that the assaulter’s negligence is not merely a minor offense but a serious crime that took a precious life and that he should bear responsibility for the rest of his life and make amends without running away,” Takahashi’s mother said in a written statement provided by Goto.

Goto did not provide names of the family members, who he said wanted to preserve their privacy.

A spokesman for Naval Forces Japan, Cmdr. Paul Macapagal, confirmed that a Yokosuka-based sailor was involved in a traffic collision that day but declined further comment, citing the ongoing investigation.

The family filed the lawsuit ahead of criminal charges to ensure that legal documents could be delivered to the sailor, a step taken due to problems Goto said he encountered in a similar case.

Goto also represents the family of Tsubasa Ito, who died after a collision with another Yokosuka sailor, Petty Officer 2nd Class Jaden Edwin Llanos. He was convicted in May of negligent driving causing death and received a suspended 1 ½-year sentence.

Llanos has since left Japan, preventing a civil suit from moving forward because the court cannot serve him with the documents, Goto said.