Oooku de Nagusamete.: Shougun to Yonin no Yotogi Hanatachi

Mikoto, a third-year high school student, gets into an accident. When she wakes up, she finds herself transported to a parallel world reminiscent of the Edo period! After meeting Shogun Yoshitaka, Mikoto is welcomed into the inner palace. There, she finds four men waiting for her to soothe her "heat"...!? A Japanese-style fantasy x doting erotic reverse harem romance!

(Source: Hakusensha, translated)