https://www.cmoa.jp/title/215942/

Koharu Shinohara is a kindergarten teacher who's concerned about her weight. After her co―worker recommends personal training, she signs up for the gym and meets a strict trainer named Shusuke Kazami. He looks a bit scary, but he's a stoic and serious guy, and Koharu begins to fall for him. Even though it's part of the training, Koharu heats up wherever he touches her, and she begins to feel things she's never felt before. Shusuke is also harboring the same feelings. This is a thrilling love story that starts in the gym.