No, Hito means "one".Really? Hito = sea lion (somehow)? You learn something new every day.
So the name would be "Hito" (one person, sort of) "Maru" for boy/son, and then stick a sealion reference between them.
アシカ Ashika is Japanese for sea lion.
So if your theory holds through, Miju 3 will have a name like "Hitoashimaru" or something like that.