Nagato Yuki-chan no Shoushitsu

Slice-of-school-life drama animes with nice comedic elements and very similar protagonists. Will certainly be a good watch for people who like silly comedy, romance and mystery. 

Two highschool romcoms with similar characters and situations. Will certainly be enjoyed by people who like this sort of animes with ups and downs and a lot of silly comedy. 

Both explore the MC's feelings toward someone precious to them. In Nagato's case, it's the typical school romance. Violet's is a more encompassing concept of what love is, and what it means to her. Both also have very good soundtracks. 

Both are comedic Spin-offs from popular Animes, which gain their strenght from their references to the main shows. They are both good at what they are doing. 

Both disguise themselves as strictly light-hearted, slice-of-life shows where barely anything interesting happens. Eventually turns out that there's more to them than what we can see on the surface (aka first few of episodes). Both of these series' main arc/conflict kick in midway through which are consisted of dramatic events. Still, keep in mind that both of them are Slice of Life shows down to the core. The difference is that Nagato Yuki-chan is a spin-off from a main series and Inou-Battle is an original series. Prior knowledge is required for the former but isn't expected to be in any way similar to the main series.  

Similar dynamics between the two main characters. Both anime feature a purple-haired shy girl who secretly have a feeling for the guy who always accompany them, try to be closer, and both also have a female friend who tries to matchmake them. These two shows' genre are comedy with romance, but more in cute and fluffy way. 

The literature club in Yuki-chan starts off really quiet, and the growth is catalyzed by a mysterious student. The SSS from Angel Beats starts off lonely and angry, and the growth is catalyzed by a mysterious dead kid. 

The main female Nagato and Mirai act similar in a way. They are both in a literature club. In Kanata it has supernatural powers and romance. While in Nagato only slice of life and romance. Originally Haruhi series was done by KyoAni. Who also did Kyoukai no Kanata. But now its a new Studio.