[5] In high school, he became guitarist in a rock band named Night Meeting, which played a show every two or three months.

[5] Mashima was eventually indefinitely suspended from school due to his delinquency and, after reflecting during this time away, decided he would try to make it as a professional manga artist.

[6] In 1998, Mashima created the one-shot manga Magician while working part-time at an arcade, and entered it into a competition held by Kodansha's Weekly Shōnen Magazine.

Mashima began Fairy Tail in Weekly Shōnen Magazine in 2006 and it went on to become one of the best-selling manga series in history with over 72 million copies in print.

In 2011, Mashima created a crossover manga between Rave Master and Fairy Tail published in the May issue of Weekly Shōnen Magazine.

[10] A special 2013 issue of Weekly Shōnen Magazine featured a small crossover between Fairy Tail and Nakaba Suzuki's The Seven Deadly Sins, where each artist drew a yonkoma (four-panel comic) of the other's series.

Another spin-off manga titled Fairy Tail Side Stories[broken anchor] and created by Kyōta Shibano launched on July 30, 2015, in Kodansha's free Magazine Pocket mobile app.

[19] Mashima's Japanese-style epic fantasy one-shot Hoshigami no Satsuki was published in the September 17, 2014 issue of Weekly Shōnen Magazine.

[24] Mashima drew a one-shot manga adaptation of the video game Dragon Quest XI S: Echoes of an Elusive Age for the October issue of Shueisha's V Jump magazine, which was released on August 21, 2019.

[29] Mashima speculated his desire to include strange and surreal mascot characters in his works, such as Happy, was influenced by Utsurun Desu author Sensha Yoshida.

[31] For Rave, Mashima's inspiration was wanting to travel the world, while for Fairy Tail it was simply sitting in bars and partying with his friends, the community aspect, but is also about young people finding their calling.

He revealed his schedule for Fairy Tail was script and storyboards on Monday, rough sketches the following day, and drawing and inking Wednesday through Friday.

[29] Mashima's assistants included Miki Yoshikawa, who has gone on to work on the romantic comedies Yankee-kun and Megane-chan (Flunk Punk Rumble) and Yamada-kun and the Seven Witches.