Reposting from the other thread...
Little primer on Japanese writing... there are 3 things you need to know.
1. There is a group of 46 "letters" named the Hiragana, which represent syllables. せ is "se", よ is "yo", etc. These are usually only 1 or 2 stroke each, and the only way to learn them is by rote memorization, as there is no pattern to them.
2. There are another 46 of these named the Katakana. These are the exact same in terms of pronunciation, but are used mainly for foreign loanwords. セ is "se", ヨ is "yo."
3. Kanji. This is the big one. You will need to learn to recognize about 2100 of these, also known as the Jouyou list. There are several ways to go about doing that, but the most popular way is to use James Heisig's "Remembering the Kanji" book, along with an SRS program. That stands for spaced repetition system, and it's a fancy way of saying electronic flashcards. I would recommend "Anki" for that, as would most people.
Disclaimer... when you are learning hiragana there will be a point where you get really frustrated and will despair at having to learn 2100 of them in kanji form later. This is not true, because kanji are set up in patterns and building blocks that make them easier to learn. You'll understand this more as you make your way through "Remembering the Kanji", assuming you go that route.
Tons of people have gone into this stuff in more depth... you can learn a surprising amount from Wikipedia. Good luck, and if you have any more questions feel free to ask.
By the way,
>>4, I like most of what you said, but I disagree that his reasoning is weak. I don't see the difference between learning it to read VNs and learning it to read, say, classical literature. If he's interested enough in those VNs, that'll form the basis of his dedication just as much as liking classic literature would for someone interested in it.