The anime revolves around Hana Ichinose, who is secretly a year older than her classmates. She was held back a year because of sickness.
The original is a four-panel manga series by Tuiko Tokumi. It is running since 2013 and has released 4 volumes as of November 2017. It is being serialized in Houbunsha’s Manga Time Kirara.
Opening: ne! ne! ne! by STARTails☆
Ending: Kaze no Koe wo Kikinagara bySangatsu no Phantasia’s vocalist Mia