>>92628
It was colored by americans for a US release. It has nothing to do with Otomo or the original manga. They did a digital "re-coloring" for virtually every popular manga by now, from Naruto to Jojo.
To answer your question, an actual full color manga is extremely rare. For one thing, it's very time consuming - unlike american comics, japanese manga is created entirely by the author himself aided by a small team of assistants, and sometimes not even that. Then there's also a matter of release, the most popular manga are the weekly ones, it's impossible to produce a fully colored chapter every week by a team of ~4 people, though there are a few precedence of an author at the peak of his craft doing a fully colored chapter, for example, Kubo did one for Bleach at the end of the Soul Society arc - https://mangadex.org/chapter/50517/3
As for monthly, bi-monthly and so on manga, there are a few examples here and there, for instance, Saint Seiya Next Dimension - https://mangadex.org/chapter/411531/1
There's a matter of publication as well, all manga are first published in magazines, which are printed with cheap recyclable paper and look like absolute shit. Later manga is reprinted in individual volumes with good paper. But that's actually one of the main reasons why manga is black and white, it's cheap to produce. And considering how much manga is produced on a daily, that's a serious matter. Imagine a >500 page magazine with all color pages, or hundreds of manga volumes released each month that are all colored and require good paper to boot.
There is also such a thing as bichrome manga, when the third color - red and its shades - is added to the mix, resulting in a faux "colored" look. This was practiced largely in the 80s and 90s, not so much now.