Seijohs

Seijoh is a term that can refer to several entities, most notably a fictional high school from the popular manga and anime series Haikyuu!! and also a historical Japanese calendar system.

In Haikyuu!!, Seijoh High School, officially known as Aoba Johsai High School, is a prominent volleyball team and a rival to the protagonist Karasuno High. The team is recognized for its strong performance and its ace player, Tooru Oikawa. Seijoh's distinctive green and white uniform is a recognizable element within the series. The school is depicted as a well-established institution with a competitive spirit in sports.

Historically, Seijoh refers to the Seijoh calendar, also known as the Kōreki calendar. This was a lunisolar calendar used in Japan from 1645 until 1872, when it was replaced by the Gregorian calendar. The Seijoh calendar was an improvement upon previous Japanese calendars, aiming for greater astronomical accuracy. It was based on astronomical calculations and was designed to better align with the seasons and lunar cycles. The development and implementation of the Seijoh calendar represented a significant step in Japan's scientific and calendrical history.