In writer's humble opinion, there's many reason why kanji is difficult to remember/learn. From many reasons that can be found, I want to tell a few of the reasons that I experienced, those are because;

1). Many kanji character has similar shape with only a slight difference

2). On'yomi and Kun'yomi

3). The way something is pronounced is the same but different character to represent the word

Continue from part 1, in this part 2 I want to tell you a little bit about on'yomi and kun'yomi, and how difficult it is to evaluate words that's being used/pronounced the same many times. I hope for you who read this could get a little picture of the challenges you might encounter in learning Japanese language.

On'yomi and Kun'yomi is a difference between how to pronounce the words in Japanese language. The kanji itself is a writing/character from a result of absorbing Chinese writing/character. Japan loves China so much in the past to the point of reusing Chinese language for themselves, localizing the writing/character so it would fit the Japanese tongue. Do you already have a clue of what they changed? Yup, they changed the pronunciation of the writing/characters.

1. On'yomi : Reading derived from the Chinese pronunciations.
2. Kun'yomi : Originated readings by Japan.

That's the reason of why when you learn the Japanese language, you often to see the same characters in Chinese language but pronounced different.

Below is the examples of kanjis with their different pronunciation (with meaning):