Kazuki Anaguchi has passed away at just 23 years of age.

The Japanese Boxing Commission confirmed the tragic news that Anaguchi was pronounced dead Friday evening (local time) while still hospitalized in Tokyo. The once-promising bantamweight prospect never regained consciousness from injuries sustained in a December 26 unanimous decision defeat to countryman Seiya Tsutsumi.

The ESPN+/Lemino aired bout saw Anaguchi go all-in during a Fight of the Year candidate between unbeaten Japanese bantamweights at Ariake Arena in Tokyo. However, the memorable clash produced a horrific post-fight visual as Anaguchi’s legs began to twitch as medical attention was paid to a gruesome cut over his left eye.

Anaguchi was taken to a nearby hospital, where he fell into an unconscious state before he arrived in his assigned room. Doctors performed an emergency craniotomy to remove a subdural hematoma on the right side of his brain.

Anaguchi was game throughout and outfought Tsutsumi in several rounds in his challenge for the Japanese bantamweight title. However, he was dropped in rounds four, seven, nine and ten which ultimately produced the margin of victory for Tsutsumi (10-0-2, 7KOs) by scores of 95-91, 94-92 and 94-92.

The bout took place on the undercard of the Naoya Inoue-Marlon Tapales undisputed junior featherweight championship at Ariake Arena in Tokyo. The boxing world immediately rallied around the locally based Anaguchi (6-1, 2KOs) but is now left to mourn his untimely passing.

Anaguchi was a talented amateur boxer based in Osaka.

He was just six years old when he first took up the sport and went 68-8 as an amateur. A failed bid to qualify for the delayed 2020 Tokyo Olympics prompted a year-long pause in his boxing journey. He opted to instead turn pro in July 2021—fittingly at the start of the Olympics.

The talent was evident early in Anaguchi’s career, particularly in a December 2022 eight-round shutout of former three-time title challenger Jonathan Taconing in just his fourth pro fight. The regional title fight versus Tsutsumi was his first scheduled ten-rounder, though a natural course of progression in his career at the time.

Anaguchi leaves behind a one-year-old daughter, with whom he hoped to spend time with on a family trip following the Tsutsumi bout.

The BoxingScene.com staff offers its heartfelt condolences to the Anaguchi family.

Jake Donovan is a senior writer for BoxingScene.com. Twitter: @JakeNDaBox