Ippei Mizuhara, the former interpreter for Japanese baseball star Shohei Ohtani, will face up to 33 years in jail when he pleads guilty to stealing millions of dollars from his former friend.

Mizuhara has admitted to one count of bank fraud and one count of subscribing to a false tax return. As well as a length jail term, he must also pay $16,975,010 in restitution to Victim A, assumed to be Ohtani. Mizuhara will enter his guilty plea in the coming weeks and is set to be arraigned on 14 May, prosecutors said.

Ohtani and Mizuhara became close friends beyond their working relationship after the player moved to the US from Japan to begin his Major League Baseball career with the Los Angeles Angels in 2018. That relationship continued when Ohtani crossed LA to join the Dodgers on a 10-year, $700m deal last December. But Mizuhara was fired by the Dodgers in March after admitting that he stole at least $4.5m from Ohtani, the biggest star in baseball, to pay off gambling debts.

Reports have said the plea agreement would include an admission that corroborates Ohtani’s version of the events – that the player never wagered on sports, had no idea that Mizuhara did so and was the victim of a “massive theft” by his former friend. MLB players are forbidden from betting on baseball, and face a lifetime ban if found to have placed a wager on their own team. They are allowed to bet on other sports in the nearly 40 US states where gambling is legal, but not in California, where Mizuhara and Ohtani are based. There is no evidence that Ohtani ever placed any wagers himself or was aware of Mizuhara’s gambling.

Mizuhara exploited his relationship with Ohtani to plunder millions from the star’s account for years, at times impersonating Ohtani to bankers, prosecutors said. Mizuhara’s winning bets totalled over $142m, which he deposited them money into his own bank account and not Ohtani’s. But his losing bets were around $183m, a net loss of nearly $41m. He did not wager on baseball.

The theft became public knowledge when wire transfers from Ohtani’s bank account were discovered in a federal investigation of an alleged illegal bookmaker. Mizuhara initially said that Ohtani agreed to cover his gambling debts, then backtracked and admitted that Ohtani was unaware of the payment to the bookie in California.

Ohtani, a rare player who excels as both a pitcher and hitter, is one of the most famous people in his homeland. The scandal does not appear to have affected his performance on the field. He leads MLB in home runs and batting average and the Dodgers are top of their division, the National League West, by six and a half games.