Talk:Nagato/@comment-210.186.52.102-20170309114207/@comment-26850872-20170309120325

The "mon" in "Nagamon" is another method of reading the Kanji associated with her name, as we can also read the kanji as "mon." From fan reception of Nagato's characterization this (mis)reading of her name seems to have stuck towards depictions of Nagato acting that way (going kyaa kyaa over cute things) instead of being a direct reference to the Kumamon bear mascot as you suggested.

I am sticking to this definition on the basis of "why fans nicknamed her 'Nagamon',", but some other people might be able to agree with you.