OK, I think I can make something like that work (though neither Renka nor Miu have an assignment, per se.)
Further context:
Shirahama Kenichi was a bullied kid until he met a marvelously talented girl, Fuurinji Miu (the blond girl), a new transfer to his 1st year high school class, who teaches him a technique that lets him beat a muscleman in the karate club he's in who had challenged him - loser has to quit the club. Although Kenichi beat him, Kenichi quit the club, stating that what he used wasn't karate, so was cheating, but then the vice president of the club, his interest piqued by Kenichi's sudden improvement, sets out to test his mettle. Miu tells him of a place that can help him, which turns out to be the dojo where she lives - Ryouzampaku, the gathering place of masters who take martial arts to extremes. Among them are the karate-ka, "100th Level Brawler" Sakaki Shio (in the first panel above), and Renka's father, Ba Kensei, Master of All Chinese Kempo, who had been the head of the largest martial arts organization in China, but had abandoned it and his family when it became too much of a hassle, and Miu's grandfather, the Invincible Superman, usually just called "the Eldest" 長老 or "Old Man" じじい. Renka had been living in Yokohama Chinatown, trying to track down her father, when Master Ba (with Kenichi trailing him) shows up there, tracking down rumors of his older brother, the black sheep of the family.
Renka showed up the previous night, just as Kenichi was feeling inadequate because all his friends seem to have special, named finishing moves, but he doesn't, and Renka told him that he should come to him to a place where he could get the one thing lacking in his training...
That place being the water park, where he can relax, but the masters had tracked them there, and put him through some "light" training (treading water holding weights above his head, climbing up a water slide, punching and kicking in the water while walking the length of the 50 m pool 100 times...)