Isshī

"おいらは イッシー. カメの ばけものが、現れて、仲間はみんな石にされてしまったのです. (I'm Isshī. A turtle monster appeared, and all my friends were turned into stones.)"

- Isshī

Isshī is a character that appears in the last chapter of Super Mario-kun volume 1 as the guide of Super Mario Bros. 5, the hypothetical sequel Mario, Luigi, and Yoshi end up in.

When the heroes arrive in Super Mario Bros. 5, Mario sits on a stone, which yells at him. The stone presents himself as Isshī, an inhabitant that was turned into stone, alongside his friends, by Bowser, who kidnapped the princess. Mario decides to help him and the princess, exploring this new adventure's elements, guided by Isshī, who carries Luigi and Yoshi on his back, flying to help them follow Mario when he becomes Hata Mario, and giving him power-ups and information on the new enemies.