Gama-chan

is Naruto Uzumaki's toad shaped wallet. Gama-chan's presence and brief appearances in the series are used for comic relief. Naruto cares for "Gama-chan" and refers to it as if it were a pet, saying that it's happy when it's fat and full of money. He gets disappointed and indignant whenever Jiraiya's jaunts out for "research" would end up with Naruto broke, and Gama-chan emaciated.

When Tsunade made a bet with Naruto on whether he could master the Rasengan in a week, she took a money-filled Gama-chan as his part of the wager.

Gama-chan continued to survive the wear and tear (and feast and famine) of the years. As a father, Naruto continues to pay for out-of-pocket expenses through Gama-chan.

Trivia

 * During the Three-Tails' Appearance, when Naruto asks Konohamaru to buy snacks for Gamatatsu and Gamakichi, Gama-chan's eyes lack the white border around them.
 * On the underside of Gama-chan, a white strip can be seen. The strip roughly says.
 * It might be based on the Chan Chu, the Lucky Money Toad, a Chinese symbol of prosperity depicted as a frog sitting on top of a pile of coins with a coin in its mouth.
 * The Japanese word for frog, "kaeru", is a homonym that means "return / to return". It is considered lucky in Japanese culture to keep a frog in wallets (in whatever form, whether as figurines or keychains, etc.) for money to come back when it is spent.
 * The creator of Naruto, Masashi Kishimoto, says "One day, the following incident took place. I got stuck writing a manga just before the deadline, so I lay down behind my desk to take a short nap. When I was looking for something to use as a pillow, I found a big frog-shaped gamaguchi cushion. (This is a cushion modelled on the froggie wallet that Naruto uses in the series, it was made as a present for readers.)"
 * In several Ultimate Ninja Storm series, Gama-chan appears as a custom Substitution item. In Ultimate Ninja Storm Revolution, it also appears as a character customisation accessory for Naruto.