Isekai Enkou - After

Soldiers, aristocrats and alchemists. These are men you would never see in modern Japan.

Shiori is about to have a “love affair” with one of these men. Shiori, who is active in the track team, has a best friend, Yua. Yua is a childhood friend who belongs to the cheerleading club at the same school.

When Yua loses contact during the summer vacation, Shiori worries about her, but when the second semester starts, she finds out that she has been involved in compensated dating.

When Shiori expresses her indignation, she hears an unbelievable story from Yua mouth. Yua had been doing compensated dating in a "different world". Shiori still not believing the story is shown by Yua the door that leads to the other world.

[From official site]