Rin is a Mii from the Wii.
Rin originally appeared as one of the 60 CPU Miis to be included with Wii Sports. Since then, she'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, her internal ID is 018, however in Wii Music it is 58. Her Mii data filename is cpu_mii_018.rcd in Wii Sports, mii_018.rsd in Wii Sports Resort, Wii Fit, and Wii Fit Plus, mii_018.ffsd in Wii Fit U, and is cpu_mii_db58.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, she does not have a creator name or birthday, and has Mingling turned off. Her Mii name in her Mii data file is りん. In her Wii U/3DS-format Mii data file, she was originally created on a Wii (1).
Her Mii data file does not contain any unused data.
In Wii Music, her 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. Her Mii ID is 80-4f-9a-4f and her console ID is c2-3d-21-af. Her Mii ID tells us she was created on August 30, 2006 at 12:29:48 PM.
According to a September 2020 Nintendo leak about CPU Miis, Rin's nationality is Japanese (Asian).
In the files for Wii Sports, her dominant arm for Baseball (Batting) is left-handed, Baseball (Pitching) is left-handed, and Tennis is left-handed. Her unused dominant arm for Boxing is left-handed. Her Baseball Pitching style is normal. She's ranked 11 in Baseball, 53 in Boxing (meaning she doesn't appear in Boxing), and 43 in Tennis. Her group IDs are 8, 0, and 1.
In the files for Wii Sports Resort, her Wii country ID is 1, like all CPU Miis. Her dominant arm for Table Tennis is right-handed. She's ranked 2 in Swordplay, 59 in Basketball, 37 in Table Tennis, and 67 in Cycling. Her unused Canoe and Debug ranks are both 18, matching her ID value of 018.
Rin appears in promo art for Wii Music playing the piano and Wii Party playing Board Game Island. For some images, you may have to open them in a new tab to see the whole render.
Note that in her Wii Party render, she's wearing her favorite color (sky blue) instead of the favorite color.
Names in other languages
Source: Wii Sports Resort