Kentaro is a Mii from the Wii.
You may get them confused with Kentaro (Wii U/3DS)!
Kentaro (Wii) originally appeared as one of the 60 CPU Miis to be included with Wii Sports. Since then, he's appeared in Wii Sports, Wii Sports Resort, Wii Party, Wii Music, Wii Fit, Wii Fit Plus, and Wii Fit U. In most of these games, internal Mii ID is 008, however in Wii Music it is 48. His Mii data filename is cpu_mii_008.rcd in Wii Sports, mii_008.rsd in Wii Sports Resort, Wii Fit, and Wii Fit Plus, mii_008.ffsd in Wii Fit U, and is cpu_mii_db48.rsd in Wii Music. Wii Party combines all 100 Mii data files into one larger file named mii_rsd.bin in the same ordering as Wii Sports Resort.
As with every CPU Mii, he has Mingling turned off. His Mii name in his Mii data file is けんた ("Kenta"). In his Wii U/3DS-format Mii data file, he was originally created on a Wii (1).
His Mii data file does not contain any unused data.
In Wii Music, his Mii data file is slightly different. While it's mostly the same as it is in Wii Sports Resort, it now includes a filled out Mii ID and console ID. His Mii ID is 80-4f-95-c8 and his console ID is c2-3d-21-af. His Mii ID tells us he was created on August 30, 2006 at 11:12:32 AM.
According to a September 2020 Nintendo leak about CPU Miis, Kentaro (Wii)'s nationality is Japanese (Asian).
In the files for Wii Sports, his dominant arm for Baseball (Batting) is right-handed, Baseball (Pitching) is left-handed, and Tennis is left-handed. His unused dominant arm for Boxing is left-handed. His Baseball Pitching style is normal. He's ranked 54 in Baseball, 36 in Boxing, and 30 in Tennis. His group IDs are 8, 0, and 0.
In the files for Wii Sports Resort, his Wii country ID is 1, like all CPU Miis. His dominant arm for Table Tennis is left-handed. He's ranked 53 in Swordplay, 92 in Basketball, 15 in Table Tennis, and 93 in Cycling. His unused Canoe and Debug ranks are both 8, matching his ID value of 008.
Kentaro (Wii) appears in promo art for Wii Music playing the taiko drum.
Note that in his Wii Music render, some parts look slightly off. His teeth have a much more rounded look than they do normally.
Names in other languages
Source: Wii Sports Resort