Happens All the Time

Hitoribocchi no Marumaruseikatsu

Aru attempts to save face in front of her friend Hanako Yamada after she accidentally brings an elementary school backpack to school with her. Things become more difficult for her the next day when she ends up wearing a full elementary school uniform. Later, Aru is challenged to a tennis match by Nako, finding it difficult due to all the times she's been skipping tennis club.