J.J. & Jeff

Sort of an Adventure Island-esque platformer.

Regional Differences
The original Japanese version of the game is loosely based off a television show from comedians Cha Kato and Ken Shimura. When the game was eventually released in the US years later, the main characters were understandably changed and most of the game's toilet humor was removed.

Title Screen
The title graphic for the Japanese version changes colors, while the US version remains the same color. The city in the background has been slightly modified too.

Main Characters
Here's the characters you can play as. Ken-chan/Jeff runs faster than Kato-chan/J.J., but has less traction.

The fart attack, performed by simply crouching, was changed to a spray can attack. This means the "gas" was changed from shooting behind your character to in front.

Partner Encounters
Throughout the game, you'll frequently find your partner (the character you didn't choose) either doing something lewd or even impeding your progress by throwing cans at you. Either way, you can give them a swift kick to get them to stop.

You can occasionally find your partner bouncing up and down, urinating on the background. This was changed to him just awkwardly standing there with his back to the camera, bouncing up and down with his hands on his hips.

You can also find your partner taking a dump behind a bush. Their face will turn red, signifying... strenuous activity. This was changed to, oddly enough, you partner just sitting back there wearing an animal mask.

Hint Rooms
You can also find your partner in certain doors where he'll refill your vitality meter and give you a hint or crack a joke. In these scenes, your partner is dressed in a weird outfit, most of which were changed for the US release.

Ending
After the short ending cinematic, the game begins to show all the enemies in the game. It displays the enemy's name and a short description, both of which were changed for the US release. The Japanese version oddly uses English for the descriptions, despite the rest of the dialogue in the game being in Japanese.

The credits are mostly identical, except for these last two screens. The people credited in the "very special thanks" were changed and a hyphen was added between "good" and "bye".

Finally, the ending screen itself was changed completely, and is far less disturbing.