WARNING: The following contains spoilers for RE-MAIN Episode 4, "This Ain't Looking Good...," now streaming on Funimation.
It looked like all hope was lost when Amihama defeated Minato in their swimming competition in Episode 3 of RE-MAIN, only for him to unexpectedly changes his mind and join the water polo team after finding a genuine goal to aim for.
Although the team has been fully assembled, they still have a long way to go before they can truly reach their potential. While training is a great way to improve, it can only get them so far. What Minato's team needs is experience -- and as Episode 4 shows, a practice match is the best way to get it. If only they could find some more age-appropriate opponents to test that experience on.
After losing to Amihama, the team is despondent and makes half-hearted attempts to convince him to join the water polo club anyway, but he refuses. They wonder whether it's because he beat his brother when he joined the swim team, but it's actually the opposite. Amihama joined the swim team with the purpose of beating his brother but was never able to do so. He'd been chasing that goal for years but ever since his brother switched to water polo, Amihama has been waiting for him to return to swimming.
Meanwhile, Minato's friends from Shogakukan come to visit. They're all delighted to see him return to water polo, thinking this means his memories have returned. Minato is frustrated that he still can't remember anything past the sixth grade and fears he'll remain like this forever. At this, Riku Momosaki adamantly says Minato will become the main player again -- re-main rather than remain.
Amihama suddenly appears and declares he'll join the team after all, especially after seeing Riku again. He's determined to beat his brother and if that means joining the water polo club, then he'll do it.
The team gets started on training but, fully exhausted by the end of their sessions, it's clear they still have a long way to go. The only thing keeping Minato afloat (pun intended) is his constant reminder to himself that he's a prodigy. Now that they have a team assembled, the new goal is to get their first win. Jo arranges a practice match against Rikka Gakuen, the neighboring school, in preparation for prefecturals. Amihama provokes the club's three members, calling them weak which thoroughly annoys them. However, Minato's team isn't playing against the high school team -- they're playing against the junior team.
The three high school team members had deliberately arranged the match so they could observe Minato's team from afar. It turns out Minato once played against them, but he can't remember it. The team plans out their strategy and each member takes his respective position, with Minato as the core of their offense and responsible for scoring goals. Their junior opponents may be younger and smaller but what they lack in physique, they make up for with experience.
The junior team scores their first point right off the bat, utilizing their amazing teamwork and shocking Minato's team. As RE-MAIN continues, they'll have to figure out how to work together and find a way to get back into the game.