 Sanrio are kinda shady in that they don't like to publicly share who actually designed the character but rather just say it's a character by Sanrio. However a quick google search will show that Gudetama was created by a 26 year old designer in a company called Amy or Emi Nagashima, simply inspired by an egg she saw whilst cooking dinner after a long day of work. This was part of a company-wide design competition to create a character based on food and the egg lost to a piece of salmon called Kirimi-