Ai Mai MiI: Surgical Friends
Technically it’s a sequel, but practically it’s Ai Mai Mii.
Kirakira☆Precure A la mode
Every recent PreCure season is a stand-alone series with their own protagonists and story. Not previous knowledge is needed for the series.
KonoSuba 2 is a direct continuation that picks right up where the last season stopped.
Little Witch Academia (TV)
Rewrite: Moon and Terra
Moon and Terra are two routes of the Visual Novel. The first season was there to set up characters and setting, though it is recommend to actually play the game to understand what exactly happened as the first season left many anime-only viewers confused.
Shouwa Genroku Rakugo Shinjuu: Sukeroku Futatabi-hen
Shouwa Genroku Rakugo Shinjuu continues it’s story directly.
Super Lovers 2
The second season of Super Lovers directly continues the previous one. As such watching it first is mandatory.
Tales of Zestiria the X 2
Tales of Zestiria is split-cour, meaning it was directly conceived to be directly linked.
Yami Shibai 4th Season
Yami Shibai was always a series with mostly independent episodic stores. As such the fourth season is good to pick up by itself, even with the little bit of connection from the third season.
Yowamushi Pedal: NEW GENERATION
Despite the “New Generation” subtitle the current season of Yowamushi Pedal remains a direct sequel.