Trinity Seven (Japanese: トリニティセブン 7人の魔書使い, Hepburn: Toriniti Sebun: Shichi-nin no Masho Tsukai; literally "Trinity Seven: The Seven Magicians") is a fantasy romantic comedy manga series written by Kenji Saitō and illustrated by Akinari Nao. It has been serialized in Fujimi Shobo's shōnen manga magazine Monthly Dragon Age since 2010 and collected in thirty-four tankōbon volumes as of April 2026.

A light novel adaptation by Kenji Saitō with illustrations by Akinari Nao is being published by Kadokawa Shoten, and the first volume was released in November 2014. An anime television series adaptation by Seven Arcs Pictures aired on TV Tokyo from October to December 2014. An anime film adaptation titled Trinity Seven the Movie: The Eternal Library and the Alchemist Girl premiered in February 2017. A second film adaptation titled Trinity Seven: Heavens Library & Crimson Lord premiered in March 2019.

Arata Kasuga lived a normal life together with his cousin and childhood friend Hijiri Kasuga in a small town. However, everything changes on the day of the Black Sun, which caused the Breakdown Phenomenon which destroys the town where he lived and takes Hijiri away. As Hijiri starts disappearing, she hangs a grimoire around his neck, asking it to protect Kasuga. Shattered by losing Hijiri and all of his other friends and family, Arata asks for his world to be good again, which leads to the grimoire artificially reconstructing his normal life and making him forget both the destruction of the city and Hijiri's disappearance. Lilith Asami, a mage, is sent to investigate the ruins, and she finds the powerful spell in their stead. She makes Arata remember the actual events, and consequently the spell is broken, but not without the grimoire telling him that Hijiri is still alive. Arata decides that his only option is to become a mage himself so he could rescue Hijiri, and so he joins the Royal Biblia Academy, a secret school for mages that deals with magical issues around the world. There he is introduced to the Trinity Seven, seven powerful mages who are at the top of their respective fields (Lilith being one of them) and who will help him in his goal of becoming a powerful magician and learning the truth about Hijiri and the Black Sun. He soon finds out that one of the Trinity Seven, Arin, looks almost exactly like his missing cousin, although she shows a completely different personality.