I recognize most from the right side of the illustration. It should be Dahlia Rossetti from Dahlia in Bloom and Zeros Merlin (Osako Satoshi) from Arafoo Kenja no Isekai Seikatsu Nikki. There's also the Healer MC that I don't remember the name but I remember it is said that it is the wrong way of using healing or something in this direction.

There''s man and girl from the left, I don't remember of seeing nor read their source. Does anyone know these two character since I have an idea where I saw the illustration character on the background that I plan to read to know its background story.

A tag for Wendelin von Benno Baumeister from Hachi-nan tte, Sore wa Nai Deshou should have existed if there's one.

Zarahustra said:

I recognize most from the right side of the illustration. It should be Dahlia Rossetti from Dahlia in Bloom and Zeros Merlin (Osako Satoshi) from Arafoo Kenja no Isekai Seikatsu Nikki. There's also the Healer MC that I don't remember the name but I remember it is said that it is the wrong way of using healing or something in this direction.

There''s man and girl from the left, I don't remember of seeing nor read their source. Does anyone know these two character since I have an idea where I saw the illustration character on the background that I plan to read to know its background story.

A tag for Wendelin von Benno Baumeister from Hachi-nan tte, Sore wa Nai Deshou should have existed if there's one.

Added tags for Dahliah Rossetti, Victoria Seller from Tefuda ga Oome no Victoria (the girl front left), Nick from Ningenfushin Boukensha-taschi ga Sekai wo Sukuu you desu (boy far background, right) and that guy with the super long name you mentioned last.

There's also Azuma Hiroshi from Fairy Tale Chronicles (man background far left, behind Victoria Sellers), but there's no tag for him and his series yet.