The name Nika is not derived from the sound effect of laughter but comes from the archaic Kanji used to count fruit: 果 pronounced as Ka (the usage is random #果 ). So if you want, for example, to count 2 fruits, you would say 二果: Nika: 2 Fruits. We believe that the Nika fruit itself is a combination of 2 fruits: Gomu Gomu no mi, a paramecia, and an imagination/creativity type fruit.
We think we’ve already seen both fruits represented by certain aspects of Luffy’s use of the fruit.
The Gomu Gomu no Mi aspect is pure rubber, stretching and swelling, represented by the base Luffy (or let’s call it Gear 1) and Gear 3. A figment of the imagination is the creative aspect powers of Luffy that are not intrinsic to the nature of rubber (e.g. when Kaido says “Rubber shouldn’t be able to do that” in response to the movement of Snakeman’s trajectory) and is represented by varying degrees of what looks like a cloud transforming into some sort of celestial garment initially seen in Gear 2 as Vapor and Gear 4.
The Gear 5 is the culmination of both aspects of these fruits, fully synchronized and used with mastery. What started to form in the Gear 2 as a vapor is a fully formed cloud, like it was an imaginary cloud bubble in anime/manga. For the rubber aspect of Luffy’s powers, he is no longer limited by the logic from before. He is able to stretch and extend his arms up to Gear 3 size without having to swell his hand or become malleable when hit by Kaido’s kanabo.
We all know that Blackbeard ate two fruits. We’ve already seen writing about Blackbeard’s ability to eat more than one Devil Fruit and the theme surrounding the number 3 makes us think he would end up eating a 3rd fruit.
We had thought of the childhood image of Blackbeard crying in front of the crescent moon. The crescent moon in Japanese is 三日月:Mikazuki. Mika seems somewhat similar to Nika. We tried to find a connection between Blackbeard and the numbers 3 and 9 (much like Nika is 2 and 9) but without success. However, when we translate 3 fruits using archaic Kanji to count fruits, we get 三果: Mika: 3 fruits.
In the end, we suspect that the idea of 2 rivals in the Void Century nicknamed Nika and Mika because they ate more than one fruit, which most others are incapable of, seems a bit silly, but honestly , when you consider that the vacuum century is archaic and that the Kanji for counting fruits 果 is archaic, doesn’t that hit the mark?