Imouto sae Ireba Ii.

Both about writers/illustrators and loving little sisters, same genre harem/comedy  

Both have that siscon element and the guy who is a writer for some manga publishing company , the tweak here was that Imouto Sae Ireba is a alternate of eromanga sensei, where the onichan does have a siscon disorder. 

Eromanga-sensei is an anime that became a "success" of last year and won many viewers even though I did not particularly like it, Imouto sae ireba Ii has similarities with Eromanga-sensei, beginning with the protagonists, both are writers of Light Novel and participate in publishers , in both animes the protagonist has a sister, in both animes there are many characters being presented and who become friends of the protagonist, watch Imouto sae ireba Ii, is better than Eromanga-sensei.  

It's nice to understand the life of a mangaka or anime producer and watching their adventures on their profession. 

eromanga and imouto have similar themes, but imouto>eromanga in everything 

The protagonists are siscon and they are both light novel authors. 

Both series detail stories including authors and editors, and are rather similar in the key aspects. Both also somewhat act as comedies, and detail the lives of light novel writers that have or are trying to debut.  

If you want more cute sister anime, then you should not miss out on this one. Synopsis: Itsuki Hashima is a light novelist obsessed with little sisters, strictly focusing on them when he writes his stories. Despite his personality, he is surrounded by a tight circle of friends: Nayuta Kani, a genius yet perverted novelist who is in love with him; Haruto Fuwa, a fellow male author whose work has seen considerable success; Miyako Shirakawa, a good friend that he met in college; and Chihiro, his perfect younger step-brother who takes care of the housework and cooking. Together, they play strange games, go on spontaneous journeys, crack silly jokes, and celebrate each other's successes. However, each individual must also deal with their own issues, whether it is struggling to meet a deadline or coming to terms with traumatic events buried in their past. read more 

Both "Ero-manga Sensei" and "Imouto sae Ireba Ii" are about writing novels and drawing manga/art. It's interesting to find out the life of a mangaka and writer. Both main characters are siscons lol. 

The plot is pretty much the same; the life of a novelist that doesn't have much talent working day to day and encountering trouble that's got to do with little sisters. 

It has a similar vibe to eromanga-sensie but is defiantly different and is a very character driven story - NOT A SISTER ROMANCE!!! 

Both stories are about creators who are discovering their talents and do cool stuff together in the process. Romance present in both stories; however, Sakurasou is more emotional in terms of romance.  

Both have a main character trying his best to stand out at least as much as their love interest. Imouto Sae Ireba Ii's protagonist even feels like someone who has gone through everything the main chartacter of Sakurasou no Pet na Kanojo has 

Written by the same author and you can tell this is the series he really wanted to make. If you liked the imaginary sequences of Haganai, this show delivers more of those fantasies on a consistent basis, driven by more mature and emotionally complex characters. 

This anime is also a story about writing novels. Both have little sisters and weird novels about little sisters. If you liked this anime, I am sure you will find this one interesting. 

Self aware shows that enjoy taking jabs at the industries they are set in, both revolving around a protagonist with some unlikable qualities.