
If you're looking for manga similar to Balance Days, you might like these titles.
Takumi Aono really wants to be a competitive swimmer! Like, really, really, really wants to be one. Although he swims everyday, rain or shine, he's still not there yet. But when he meets a very bitter lifeguard, something unexpected happens!
Konashi is a hard-working swimming buff who's focused on becoming good enough to land himself a spot in the upcoming summer swim competition. One day while heading to the pool to swim as always, he spots a guy he's never seen before standing on the jumping board with his clothes and shoes still on. As it turns out he's Eguchi, the resident class "mystery" who's only ever attended one of his classes. As they get talking, Konashi realizes he's nothing like the rumours made him out to be and so began a quirky brief friendship that leaves a strong impression on him even years later.
Chiba Osamu and Arikawa Madoka are in the same middle school class and in the same swimming school on Mondays, Wednesdays, and Fridays. Although they have many opportunities to talk to each other, they never have for years now. They barely acknowledge each other, even though they have met hundreds of times. But when Osamu learns that Madoka is going to quit swimming school when she starts high school, something emotional starts to grow inside of Osamu. First, it began with nothing more than curiosity, but soon it blossomed into something more real. He has to tell Madoka what he is feeling before he never sees her again.
Yamato Keisuke, a promising freestyle swimmer, and Ninomiya Ami, a talented diver, are the offspring of two rival families who own confectionery shops. Two generations ago, Grandfather Ninomiya came up with an idea for an owl-shaped cake, but Grandfather Yamato quickly raised to the challenge and thought of a similar cake--but in Yamato's the owl had ears. Because they're priced the same, Yamato's extra ears were crucial, and that made the business of the Ninomiya confectionery suffer. Grandfather Ninomiya then fell ill worrying about his shop. Before his death, his last words were "I was killed by the Yamatos", and since that moment the two families have been sworn rivals.
Third-year high school student Aya, who's secretly afraid of water, manages her high school's swim club. It's her last summer as manager and her final time managing the swim club for the Inter High Meet, but perceptive Takeru figures out her secret.
Yuuichirou Mizuno was a child prodigy in swimming that hit his peak with his bigger than average body size. However, he stopped growing, leading to no improvements. He gave up on swimming, but with the help and encouragement from his friends, he started to get back at it.
Kaname Okimura wants to learn how to swim, but has been afraid to due to a childhood accident. So how does he approach his fear of water? By joining Umisho's swimming club... but as the manager. Things are easy and slow going for Okimura, until an eccentric family moves into town, literally floating their home to the shore! Okimura watches as the hyper and childish Amuro Ninagawa and her father make their entrance, only to find out that Ninagawa is as agile as a fish in the sea she lives on. Her swimming style may be unorthodox, but she's quickly recruited into Umisho's swimming club, spicing up school life and making things interesting and complicated for Okimura...