Boss (タイショーくん, Taisho-kun) A field hamster. The self-proclaimed leader of the Ham-Hams, Boss has a huge crush on Bijou. He often tries to look like he knows everything, only to have it backfire in his face.
Gruff on the outside, but sweet on the inside, this bachelor field hamster wants to be in charge. His name, Boss, may reflect what he wants to be, but he'd give his own helmet and shovel to a Ham-Ham in need. He has a bit of a temper, but he is very dependable, courageous, and nice, even shy at times (especially around Bijou). Because he is a field hamster, he is more familiar with nature and is more independent compared to the other Ham-Hams. He has even developed a field hamster sense that instinctively tells him what kind of weather is approaching. However, he cannot deal with the sea as he is prone to sea sickness. Near the end of Hamtaro: Ham-Ham Heartbreak, it is hinted that he has a small crush on Harmony. Boss really likes Bijou, but Bijou likes Hamtaro. Boss later in the series has a crush on other girl-hams such as Gelato, Oshare, and Sparkle.
- He wears his hat almost all the time, but he took it off in A New Place for Boss and Troublesome Magical Seeds.