How Heavy Are the Dumbbells You Lift?

Dismayed by a recent weight gain, first-year high school student and snack-lover Hibiki Sakura joins the Silverman Gym and decides to try weight-training after meeting the handsome trainer Machio Naruzo.

Machio explains why exercise causes one to gain both weight and muscle, Akemi teaches the importance of dynamic stretching, and Hibiki learns about Ayaka's family business.

One of Hibiki's teachers, Satomi Tachibana, joins the Silverman Gym to lose some weight, but wants to hide her secret hobby from her students. Ayaka meets Hibiki and Akemi for lunch, and notices that something about Hibiki's bento feels strange.

Hibiki and Akemi must use different equipment due to crowds at the gym. Ayaka joins them when they have no choice but to train at home. Finally, the long-awaited beach day arrives.

Hibiki enacts a personal training regimen to succeed in Sports Day. Meanwhile, Hibiki tries to win the Silverman Gym raffle.

Hibiki enters an arm-wrestling tournament with the intention of spending the prize money on a new home theatre system, and must battle a Russian named Zina.