Seijo no Hazu ga, Douyara Nottoraremashita

Anise suddenly gets a message on her phone one day asking whether she'd be willing to lend her their aid. As if responding to her thoughts, it chooses for her and she finds herself suddenly summoned into the world of an otome game. While Anise is dumbfounded at her situation, Hime, the girl who is summoned with her declares, "I'm the Saintess!" As a result, Anise is treated as useless and driven out.

If things were to continue to go on like this, then the general of the neighboring country will die. Hime, as the saint, will take over, and a tragic ending will be met. To avoid that and take her life into her own hands, Anise resolves to save the general, change the scenario, and just settle down somewhere. That was what she planned, however...

(Source: Shousetsuka ni Narou, translated)