Finished Amanchu:
Finally I found the term of slice of life sub-genre, it is called iyashikei (healing / soothing) type of anime. Basically It is very slow relaxing pace anime that rarely focus on plot or character development. At least majority of this type anime I watched are solely focus on CGDCT (cute girl during cute thing).
Sadly amanchu, is more realistic type anime with bizarre character face animation thrown in randomly that made this made this one felt jumbled up. I not really fan of this (same goes to aria series) because it feel so slow. A good alternative probably non non biyori or hidamari sketch series, but again I doubt that both count as iyashikei. Amanchu tried to go serious abit with technical knowledge of scuba diving, but abit too little.
Not a bad series, but I dont remember that I was entirely entertained by the series. It is just... happen.