- Name: Multi-Size Technique (倍化の術, Baika no Jutsu; Viz "The Art of Expansion", English TV "Expansion Jutsu")
- Type: Hiden, No rank, Supplementary
- Users: Akimichi clan
- Debut (Anime): Naruto Episode 33
- Debut (Manga): Chapter 55
This is a secret jutsu passed down in the Akimichi clan that expands the user's stomach. This jutsu increases the user's body size by using up the user's food energy, converting calories into chakra. Akimichi clan members tend to eat fattening foods and have large physiques in order to support this technique. When Choji Akimichi uses this jutsu in Part I, it gives him a very round appearance. When he uses it in Part II it increases his size, similar to the Super Multi-Size Technique.