じゃぱすた/Let's study Japanese is a YouTube channel run by Mana, a Japanese teacher who focuses on listening, JLPT grammar, and conversation practice. Mana's videos use simple cartoon animations and graphics to literally illustrate situations where the grammar might be used. There's no English used here, so these videos are truly immersion learning.
For Mana's easiest content, check out her にほんご きほん ("Basic Japanese") series, then her N4文法 ("N4 Grammar") videos. Her teaching style tends to be textbook-like, grouping verbs into "group 1," "group 2," and so on. However, these sections are sometimes broken up by the animation segments, where she acts out stories and does voices for different characters to make it more engaging.
If you're looking for organized, clear instructional videos to learn Japanese in Japanese, じゃぱすた is a great option. Among all the Japanese teachers on YouTube, Mana does one of the best jobs enunciating and speaking clearly for beginning learners. You may need to look up some basic linguistic terms in Japanese though, as well as make sure you're at a level where you can follow Japanese speech without too much difficulty.