https://web.archive.org/web/20170702141418/http://amaterasu.tindabox.net/guide/
Ixrec's Guide to Japanese

Apparently I can use F9 or ctrl-t to type ｗｉｄｅｔｅｘｔ with microsoft IME. Other F buttons do similar things.

I wonder why 青 can mean both blue and green, maybe 緑 is a later addition to the language?
緑青
青緑
there's a whole theory about this
also traditionally the rainbow was seen as having just 5 colors in east asia
(precisely due to having less recognized colors)
japan used to recognize just 4 colors initially (black, white, red and blue)
https://ja.wikipedia.org/wiki/色名#日本語の色名とその語源
https://en.wikipedia.org/wiki/Color_term#Color_term_hierarchy
virtually all languages seem to have followed this pattern
it's really green-blue but (since it's not differentiated yet)
and it was meant to be the color of plants
<- so the color of his eyes
alternatively they were meant to be all the colors of the sky
("""red""" in the traditional color scheme was very much the color of dawn/dusk)
well wiki explains as much
「アケ（朱）」「ア（明）ける」「アカ（明）るい」と同源で、夜が明けて明るくなるという意味から色の赤に転用されたもの。
white, the color of life
black, the color of death
red, the color of blood
blue, the color of her eyes

apparently you need to type wyi to get ゐ
https://www.pc-gear.com/post/wyi-and-wye/