Amae Koromo, demon of the high school mahjong world, is the first major opponent in the manga Saki. Able to oppress her opponents using the power of the moon, her physical appearance is deceptive: though she’s a year older than Saki herself, she resembles a small child, which causes her grief to no end. Those of you who’ve seen the anime and read the manga, however, might not be fully aware of just how much Koromo’s strange mix of naivete and maturity also comes across in her speech.
When Koromo speaks, the two main elements to notice are that 1) she often mispronounces words and names like a child would, but that this is contrasted with 2) she uses a heavy, heavy amount of classical Japanese idioms and obscure, old-fashioned vocabulary. So just as often as Koromo will call Nodoka “Nonoka,” and act like a spoiled brat, she’ll throw in phrases like 黄壌 (koujou, afterlife) and 神算鬼謀 (shinsan kibou, ingenious scheme). Her Japanese is so dense and difficult at times that Japanese people themselves have trouble. If you do a search for many of her lines, you’ll find even Japanese speakers asking, “What in the world is she saying?”
The result is that Koromo comes across as a girl who is very well-read and intelligent, but also sheltered and unaware of what the commoners enjoy. This, as readers of Saki know, is exactly what she’s like.
This site collects Koromo’s idioms up to Volume 8 of the manga, while this one has some other examples of her strange vocabulary. And as always, may the Haitei Raoyue be with you.