That is the "Swedish soft serve" sold at IKEA Shin Misato (Misato City, Saitama). The combination of bright blue and yellow is very novel. It's beautiful, but it may take some courage to eat it. The flavor is "yogurt x apple mango refreshing taste". According to the people who actually ate it, blue is yogurt flavor and yellow is mango flavor.
The menu is for a limited time until November 30th to commemorate the store's 5th anniversary, and the price is 100 yen. In addition, it seems that it will be sold for 50 yen today because it is "the day of the birthday" on November 19th! Congratulations to IKEA Shin Misato.
Also, at the same store, "Sweden Flag Roll" (199 yen), which has the same impressive "IKEA color" as soft serve ice cream, is on sale for a limited time until November 24th. Both menus are colored with naturally derived pigments.
I'm curious about the sweets with a color scheme that is hard to imagine in Japan. If you are near you, why don't you come visit us?