Today I picked up my first manga (Bleach) and even though it's going to take me ages to read I am looking forward plunging into the Japanese native material pool, I can't stand grammar books and core hardly anymore. So it's really great there is furigana everywhere except on some numbers, therefore my question: how do I read those numbers?. I guess if a number has no furigana is read like ichi, ni, san, shi, … but I need to ask to be sure.

In most cases. If it is followed by つ, then you use the kunyomi (hito-tsu, futa-tsu, etc.). If there is another counter involved there might be other rules. This page covers pretty much everything you need to know. I know you said you can't stand grammar books, but I'm too lazy to print all the exceptions out . Besides, you don't really need to memorize it all, you can just check the tables in there if you aren't sure about some readings.

Numbers drive me crazy as well. Apart from paying more attention to numbers in audio form, I'm not really sure how to deal with them.

Then I don't understand why they won't put furigana on numbers.

bcrAn Wrote:Then I don't understand why they won't put furigana on numbers.

Because native speakers over the age of 6 or so don't really have problems with them except for a few rare exceptions. Although it does seem a little strange that they put furigana on every single kanji except for the numbers.

@yudantaiteki
Well… that's exactly why I am asking.

Eventually you just learn the counters and can generally tell if they're sound like kango (sino-japanese words) or wago (japanese words) and then apply the sino numbers or the older japanese numbers accordingly. There will be exceptions of course and readings that sound like wago but aren't such as 匹（ひき）. But basically you just get used to these words like any other aspect of Japanese really.