I see a lot of people complaining about Tsubame calling his mother "Mother" but seriously guys Mother doesn't mean by gender only. Its because "they give birth" which is a beautiful thing in this world if u ask me. I think that is also the reason why we refer Earth as "Mother Earth" in some instances. Its just my opinion so don't hate me.
And have to say it Kuma as a mother in this series especially chap 4 is totally my mother who is so sweet, innocent and caring.
I don't like her calling him "PAPA". I don't like the intimate scenes, they don't even make me horny. So why am I reading this manga? I wonder!