Yandere Kanojo manga summary:

Tanaka Manabu is a geeky student, on the way to school he meets a girl carrying a bloody bat. That girl is Ryuuzaki Reina, leader of the school's female delinquents. It's love at first sight. A gag manga (with a combination of 4koma and normal page) about having a yandere girlfriend. Note: In this series, They use "yandere" to as a "yankee" + "dere-dere" combination. Yandere usually means something different (google it). And a "yankee" is a trouble maker, it does not refer to Americans, google that too. ** This series is serialized in two forms; The print version in Gangan Joker, and an online version. Both versions feature the same characters and settings, but different stories. The majority of the scanlations are from the online version. Scans from the print version are denoted with the .1 suffix designation.