Zombie Land Saga Gaiden: The First Zombie

Zombie Land Saga Gaiden: The First Zombie (ゾンビランドサガ外伝 ザ・ファースト・ゾンビィ) is a manga that will begin before its publication on May 19, 2021 in Ultra Jump magazine.

Plot
Eikichi Hyodo is a second-year high school student, and the eldest son of an onion-growing family. Eikichi withdrew from the Baseball Club due to injury, so he now considers his life to be mediocre and has no encouragement. On the other hand, his twin older sister, Yuko, are in perfect condition and have the opportunity to take over the family business. However, one day Yuko disappears without a trace...

Trivia
es:Zombie Land Saga Gaiden: The First Zombie fr:Zombie Land Saga Gaiden : Le Premier Zombie
 * The manga takes place in 1989, 29 years before the events of the main series.
 * This manga seems to indicate that it was based on the Christian apocalypse prophecy written in 1989.
 * Confirmed to be Tae's backstory