time for some notes from claire
in Japanese, "maru" (丸) means a circle or just something round (much like the green mascot creature here)
children or pets are often affectionately called "Maru". There was or is a pretty famous youtube cat named Maru, and if you've ever looked at the logo for maruchan instant ramen you'll see a circular face of a little boy whose name clearly must be Maru-chan