Highschool of the Dead

Highschool of the Dead (also known as Gakuen Mokushiroku: Highschool of the Dead) is a 2010 anime (12 episodes + 1 OVA) that's basically a high-octane zombie apocalypse story with heavy action, horror, and a lot of fanservice.

Quick synopsis: It follows Takashi Komuro, a high school student at Fujimi Academy, who witnesses the sudden outbreak of a mysterious virus that turns people into mindless, flesh-eating zombies (called "Them" by the characters). After a personal drama moment with his childhood friend Rei Miyamoto and her boyfriend, Takashi ends up on the school rooftop just as chaos erupts across the city and school.

He teams up with Rei, his best friend Hisashi (who gets bitten early on), the skilled spear-wielding Rei, the busty school nurse Shizuka Marikawa, the no-nonsense Saeko Busujima (kendo club president), sharpshooter Saya Takagi, and her dog-loving friend Kohta Hirano to form a ragtag group of survivors.

They fight their way out of the overrun high school, scavenge for supplies, deal with both zombies and panicked/violent humans, and try to find safety in a collapsing society — all while navigating interpersonal drama, romance hints, and plenty of over-the-top action sequences.

The series is known for its intense gore and zombie-killing scenes (produced by Madhouse with great animation), but it's equally famous (or infamous) for its extreme fanservice, exaggerated character designs, and ecchi elements mixed into the survival horror.

It's a fun, guilty-pleasure zombie romp if you like action-packed undead stories with a side of anime tropes cranked to 11. No Season 2 ever happened (manga went on hiatus and the author passed away), so it ends on a somewhat open note.