There is often a big disconnect between the grammar points that are taught in textbooks and actual Japanese you will find in the wild. This is not to say grammar study is useless or that textbooks don't teach you "real" Japanese, but it's just a fact of how languages evolve naturally and how native speakers like to break the rules of grammar fairly often.
I jokingly call these grammar points N0 Grammar because they don't show up on the 6adb84e3. It has nothing to do with their difficulty however. Some might be tricky and some might be very easy to understand as soon as you see them.
Below is a list of these common points with an attempted explanation of how they work. I don't expect my explanations to be formally correct, especially from a linguist point of view, and you should not take them as such. Especially when it comes to slang native speakers might have different perspectives too.
They are just general examples of things I've seen myself in immersion that made me go "huh, interesting".
- Use of Futari Not for People
- Use of Sugoi as an Adverb
- Use of Shiru for the Location of Things
- ta wa ii ga
- Using to to Leave Something Implied
- E as ii
- towa as With Topic vs to as With
- Imperative Form of Wakaru
- danoni Instead of nanoni
- Using 2 Superscript to Duplicate a Word
- yorosiku as Just Like
- iittekotonisiyo
- Omitting koto in a List of Actions
- Using tachi as a Generic Pluralizer
- wo puriizu Instead of wo kudasai
- ku-adjective Plus Potential Form of aru
- kiitekureyo