I'm the Demon King, but no matter how I think about it, this development doesn't make sense.

A hero has attacked the castle of the weakest Demon King. One by one, the middle bosses are defeated, and it's only a matter of time before reaching the Demon King's chamber. The panicking Demon King's aide claims to have a secret strategy against the hero... A laid-back short fantasy featuring a mediocre Demon King and his aide, with occasional appearances by the hero. This work was originally posted on pixiv under the name Kussamakura Chiwawa, and has been revised and expanded for publication here.