A sushi lunch appears a bowl of noodles or rice with two chopsticks in it including a piece of Sushi, with some type of fish on top (probably salmon or unagi).
It appears on some levels, usually in places the player has to go. When run into, the player will have one third of their health replenished.
Rubble Trouble Tokyo - One level features a destructible billboard that has a large Takeshi running, and on it a sushi lunch and the words "Final Ninja Sushi" and the bottom ends of the sign.
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The level with the sushi lunch cameo.
In Final Ninja Zero, it states that the workers in the building hid their sushi lunches from the prying eyes of the Merlock Food Company. In Final Ninja, Takeshi says that it is his favourite food, and also that workers have left them behind.