Zenshuu.

Both MCs are able to use drawings to summon monsters they created to fight on their behalf against monsters trying to destroy their worlds. These MCs use their abilities to change the fate of the worlds they are trying to protect.  

Similarities Both have citizens defending there town from monsters in a “last town left” kind of world Both has a foreign entity come into there town that knows things they don’t know Both seem to have twists and turns you wouldn’t expect Both has the town people and foreign entity join forces using foreign entities knowledge and or skill / power to try to change the town’s future for the better. Both has its own kind of quirkiness and uniqueness. Both seem overall lighthearted but with dark/ serious moments at times. Big Differences Zenshuu is fantasy , Decadence is sci-fi Zenshu is isekai , Decadence is not  read more 

-The heroine wants to prevent the male protagonist of a story from falling into despair. -Both shows tackle the relationship between an original work and its fanfiction. 

The mc of both series use their creative powers as writer/artist to overcome challenges in isekai setting. 

-both mc isekai to another world and joins a party to defeat evil from the world. -their goal is to go back to the original world -both mc has a unique power that allows them to summon any power they want with imagination -lots of very unique abilities from both series -very fun and adventurous  

-both main characters are in a way, "magical girl" who can summon power from their item -main character with love interest has similar love chemistry: bickering and teasing, but finds me interesting -is in a group to defeat evil from the world