It's technically assonance since the "ma" and "mu" have similar vowel sounds.
No, for 天龍っぱい キソっぱい as well as here. I don't know any slang off the top of my head that starts with "mu" and also restricts itself to smaller breasts; as it's restricted to just the consonants, its fine.
(As an aside - /məˈmɑː/ or /ˈmamə/ cf /ˈmʌfɪn/,or if you're from the US /ˈmɑmə/ or /məˈmɑ/ cf /ˈməfən/ means the vowels are the same in American English, and very very similar for British.... so yeah, I guess it is assonance, phonetically; huh. I did better than I thought.)
No, for 天龍っぱい キソっぱい as well as here. I don't know any slang off the top of my head that starts with "mu" and also restricts itself to smaller breasts; as it's restricted to just the consonants, its fine.
(As an aside - /məˈmɑː/ or /ˈmamə/ cf /ˈmʌfɪn/,or if you're from the US /ˈmɑmə/ or /məˈmɑ/ cf /ˈməfən/ means the vowels are the same in American English, and very very similar for British.... so yeah, I guess it is assonance, phonetically; huh. I did better than I thought.)
Either way, it's amusing wordplay. And it's stuff I love.