I think it is interesting to learn to read a new script. Many people (who are not adult language learners) don't know what it's like. I will describe how it works.
For Japanese, you start with 2 phonetic scripts called Kana. One is Hiragana and the other is Katakana.
Even though they are phonetic, they mean nothing to the newly initiated. When you start, you can't just look at the shape and figure out for yourself what it sounds like. So you have to begin a process of training your brain to give you the sound when you see the character. It's very slow at first. You study and then you test yourself. In the beginning, you wait and wait but the answer never comes to you and you must resort to looking at the answer. Soon, you get to where you can come up with the answer after several seconds of thinking about it. Sometimes you come up with the wrong answer so then you learn that you have to check to see if you are right.
Then there is the point where you get the answer after only a second but you must double-check to make sure you are correct. Some characters come quicker than others. A few seem to really resist.
Finally, you move on to reading several characters that form a thing called a word. If you read the word and understand it, then you know you read it correctly. If you don't understand what you read, you double-check your reading and then look for the meaning of the word. The best thing to do is to continue reading familiar words.
At this point, you tell all the people you know that you can read Japanese kana. But really, you can't. You still read at a snail's pace, looking at each character one-by-one. The best thing to do is to keep reading. The more you read, the faster you get. In fact, suddenly, you'll notice that the reading of the characters will pop into your head before you even start to think about it. When that happens, you may doubt yourself and think for a second to make sure that what came to mind so quickly is, in fact, correct. This is where you start building confidence and trusting yourself.
The next level you need to reach, is the ability to see more than one character at a time. When you can start looking ahead a bit, you will begin to increase your reading speed. Since Japanese doesn't use spaces, it is difficult to see where the word ends and to be able to read the whole word at once. This is where Kanji comes in. Kanji in Japanese helps divide the words up. However, if you have authentic children's books, they will be all in Kana with spaces.
Now, how about Kanji words? Well, let me tell you, it is exactly the same. What I mean is, you have to train your brain to come up with the right reading. You don't just look at the character and sound it out. But since Kanji have meaning, what you do is, look at the word, get the meaning, and then apply the reading. You DON'T get the reading and then derive the meaning. It's meaning first, then reading.
It's slow at first but you get quicker at it. Sometimes you wait for it to come to mind, and sometimes it pops into your head right away. The characters are like a signal to your brain. Once your brain is trained, you don't have to think about it. With Kanji, there is a lot of training to do. Just accept that it's going to take forever.