Letty is a Yuki-onna, and possibly the fattest youkai in Gensokyo, weighing in at 421kg at only 167cm / 5'5 height. As one might surmise from her weight, Letty has a great love for food and one can easily bond with her over it. 

Letty used to have a fittingly cold personality until she mellowed out when she came to Gensokyo, and is now humble and cordial towards most, even humans. She does not like rude or impolite people. 

As a seasonal yokai, Letty is only visible during winter.