"Glue painting?" Rather unattractive.
"Japanese single-style paintings of the modern era?" Rather limiting.
Scholars have always had a hard time defining nihonga, but recognizing this style of art is a bit like true love: You know it when it comes along. If you are not familiar with this national art form, then a visit to "Nihonga of the 20th Century" at the new Geidai Museum will be an enjoyable introduction. If you are already enamored, you will not want to miss this overview, and the first-class paintings by past and present masters.