> Wow, there is a lot of negative gatekeeping on learning Japanese in this thread. I recommend people chill out.

Any discussion of Japanese here brings out a lot of extremely defensive nerds. I don't know why this happens more with Japanese, but it sure seems to. I don't have a strong opinion on the post, and I tend to think that if you find something that works for you, when it comes to languages, you should go with it. Far be it from me to tell you that you're wrong for learning how you learn. But that said -- and as others have noted -- the explanation here is misleading, and that's because of the dependence on romaji / transliteration. Japanese conjugation is extremely simple, and the author is missing some essential context that would make it all much clearer. For example:

> it's not entirely clear what nomu's stem is. is it nomu? but then, we define stem as the unchanging part — whereas the last vowel seems to alternate, like nomi or noma in some cases.

First, there is a clear stem (飲＊), but you just don't know that yet, because you haven't learned kanji [1]. The conjugation is extremely regular, and there's no reason to memorize a bunch of granular rules like this:

> む (mu) changes to み (mi) when adding ます（masu)

To wit: a godan verb [2] shifts from the "u" sound（う・く・す・つ・ぬ・む・る・ぶ・ぐ / u, ku, su, tsu, nu, mu, ru, bu, gu）to the "i" sound in the same column of the kana table（い・き・し・ち・に・み・り・び・ぎ） when conjugating to the formal (aka "teineigo" / aka "masu"）conjugation.

It's one rule. Then, for casual negative conjugations, you shift to the "a" sound in the same column (わ・か・さ・た・な・ま・ら・ば・が). Two rules. Formal past tense, and a bunch of other tenses derive trivially from these (e.g. わかるー＞わからないー＞わからなかった / "I understand", "I don't understand", "I didn't understand"）

That covers the conjugations the author cites in the piece, and a few others that he hasn't. However, for past tense or て form, the author's system will actually confuse you (IMO), because the you really do need to have an intuition for kana to know how the conjugations are going to play out. Namely the following rules:

る・う・つ becomes って or った (continual or past tense, respectively)

く becomes いて or いた

す becomes して or した

ぐ becomes いで or いだ

ぬ・む・ぶ becomes んで or んだ

For these, it's really, really, really helpful to just know kana, and how the sounds roll off the tongue. Because if you do, you quickly see that there's really no other way for the first three endings to work out, and require little/no memorization at all. The last rows are the exceptions that you have to learn. But again, it's what...7 rules in total? In the grand scheme of language learning, this is nothing -- and boy, let me tell you, if memorizing seven semi-arbitrary things is a burden for you, Japanese is not your language.

Anyway, the point is, I strongly encourage you to learn kana as quickly as possible, and then onto kanji forthwith. The sooner you do this, the sooner all will be made clear!

[1] I am using the royal "you" here. I don't know if the author knows kanji and don't care; I'm saying that if a regular person is at this stage of learning Japanese, they will not know many, if any, kanji.

[2] Just doing godan verbs here, because ichidan verbs are much simpler. The tricky part of ichidan verbs is knowing which ones they are, which, alas, you mainly just have to memorize. You can sorta-kinda infer that a verb with an "iru" or "eru" ending is ichidan -- it's always true that ichidan verbs end like that! -- but it's a necessary-not-sufficient condition, which, again, requires that you know the kanji to distinguish "without memorization."