“I want to reach the top—in basketball.” Sou Kamino, who led his high school team to the national championship, heads to a U.S. university to become an NBA player. He continues to excel after enrolling, but... Two years later—a Japanese man is playing in a gambling basketball game in New York. It’s Kamino, now fallen from grace. Having dropped out of college for a certain reason, Kamino has hit rock bottom, scraping by day to day through gambling basketball. There’s no trace left of the shining star he once was. One day, after a gambling basketball game, a Socio (mafia member) approaches him with a proposal: “Why don’t you make some money with your basketball skills?” He is handed an invitation that reads [Ranker Game ~BASKETBALL SHOW~], indicating a 3x3 match where something is at stake. Kamino was taken to the venue and given a mission: “Lose by fixing the game.”
The match began, and he successfully made mistakes to put his team in a tight spot, but suddenly a man burst onto the court and whispered in Kamino’s ear. “You’re being set up. The loser of this match will be killed to silence them. You’ll be killed whether you lose or win. If you make a deal with me, I’ll save you.”
What decision will Kamino make... and where will his journey lead him?(Source: Amuse, translated)
— Description from AniList community (anilist.co).