Yoshifumi Tozuka is a Japanese manga artist, best known as the creator of the popular series Undead Unluck. He was born in Saitama Prefecture on August 5, 1989. Tozuka began his professional career in 2013 at the age of twenty-four, winning the 78th Treasure Newcomer Manga Prize for his one-shot Cosmic Arc Travel. The judge for that prize was Haruichi Furudate, the creator of Haikyu!!, and the one-shot was later published in Jump Next in 2014. He followed this with another one-shot, Super Heavy Charge Vanguard, which was published in Jump Next in 2015.

Tozuka spent years developing his craft before achieving serialization. A fan of Weekly Shonen Jump since childhood, he had been submitting work to the editorial department since high school. He struggled to break out for some time, but his persistence paid off when he created the one-shot Undead + Unluck, published in Weekly Shonen Jump in 2019. The positive response to this one-shot led to the full serialization of Undead Unluck, which began in the magazine on January 20, 2020. The series, his first major serialized work, ran for approximately five years and concluded in January 2025.

Tozuka has spoken about his deliberate strategy for success in the competitive environment of Weekly Shonen Jump. According to an interview with Da Vinci magazine, he calculated a survival strategy that involved increasing the speed and density of each story chapter so that his work would stand out among other titles. His artistic identity is characterized by a unique blend of slapstick comedy, intense action, and profound emotional depth. The central concept of Undead Unluck, which features characters who possess abilities that negate specific rules of the world, came from Tozuka's fascination with words that use the Japanese kanji for un-, beginning with the concept of immortality. He has stated that the rule-based nature of the world, embodied by beings called UMAs (Unidentified Mysterious Animals), was inspired by his thoughts on social media and how society might function if certain rules or systems were absent.

A notable aspect of Tozuka's artistic style is his emphasis on muscular character designs. He has explained this preference by stating that if characters are putting their lives on the line, he wants them to have muscles, and that he does not like lanky characters who rely solely on special abilities. He believes that having a special ability should also come with building good muscles. The personal experiences of the creator have significantly shaped his work. In an interview, Tozuka revealed that his mother passed away when he was twenty-six years old while he was working on a manuscript for a one-shot. He described this as the most confusing time of his life, leading him to avoid drawing manga for a while. He credits his editor for reaching out to him later, which helped him return to the craft. He has directly stated that this experience of facing death for the first time was a major factor in his outlook on life and how he portrays death and various emotions in Undead Unluck, including the protagonist Fuuko Izumo's initial suicidal thoughts.

The success of the manga led to an anime adaptation. The Undead Unluck anime, produced by TMS Entertainment, premiered in 2023. Tozuka has expressed that his initial goal was simply to survive serialization in Weekly Shonen Jump, and he was more astonished than happy when the offer for an anime adaptation came, viewing it as a huge reward for his hard work. He has also been directly involved in the franchise beyond the original manga, creating an entirely new storyline and a unique character named UMA Balance for a one-hour television special of the anime, titled the Winter Arc, which aired in December 2025. Regarding his overall philosophy for his work, Tozuka has commented, I drew this work with the intention of affirming everyone, even those in difficult circumstances.