Big Girl and Little Girl

Okii Onnanoko to Chiisai Onnanoko
大きい女の子と小さい女の子

Alternative

manga

The OL Tae Honda went swimming at the community pool, but her lack of exercise caused her to cramp up in the water, when she was saved by a tall, beautiful girl Mai Igarashi. Feeling attracted to her savior as she left the the pool, Tae saw Mai come out carrying an elementary school backpack… *Note: Includes 4 extra chapters.*