Isekai de Omake no Nii-san Jiritsu wo Mezasu

Junya is an ordinary businessman who gets caught up in a summoning of a shrine maiden and is transported to a game world. Junya is treated as an "extra" because he is summoned along with other Japanese who are then worshipped as the shrine maiden. Although he is treated coldly, he is determined to live independently in this world. However, the super-beautiful first prince, the daring knight captain, and the earnest attendant are all overprotective of Junya and try to prevent him from becoming independent...?

(Source: AlphapPolis, translated)