What is the Japanese title of the original Paper Mario?

The Japanese title of the original Paper Mario is Mario Story.

The Nintendo 64 role-playing game launched in Japan on August 11, 2000, under the title Mario Story (マリオストーリー). It reached North America in 2001 as Paper Mario, a name that better highlighted its distinctive paper-like visual style.

The game began development as Super Mario RPG 2 and was initially planned for Nintendo's 64DD add-on. Development eventually moved to a standard Nintendo 64 cartridge, and Intelligent Systems created the finished game. Its paper-inspired presentation became the foundation for the wider Paper Mario series.

A common mix-up is treating Mario Story as an informal translation. It was the game's official Japanese title, while Paper Mario was the international title. The first sequel also used a different Japanese name: Paper Mario: The Thousand-Year Door was released there as Paper Mario RPG.