Kai Ōba is the original creator of the manga Tono to Issho. This work is a yonkoma, a four-panel comic strip, that reimagines famous Japanese warlords from the Sengoku period in a comedic and parodic style. The manga began serialization in 2006, published by Media Factory in the magazine Comic Flapper.

The success of the manga led to multiple anime adaptations. An original video animation, or OAV, was released in March 2010. This was followed by a television anime series titled Tono to Issho: Ippunkan Gekijō, which aired from July to September 2010. A second television series, Tono to Issho: Gantai no Yabō, is the specific example for which Ōba is credited as the original creator and aired from April to June 2011. All anime productions were directed by Mankyū and produced by the studio Gathering. As of the available information, the manga series remains ongoing.