Saioshi wa Nobunaga-sama!! ~Time Slip shita no de, Sengoku Jidai de Oshi Katsu Hajimemashita!~

Oh no! I've lost my reason to live! Sawayama An is a high school girl who devotes herself to her idol... but then her idol suddenly goes on hiatus! Deep in despair, An slips off a bank into a river on her way to school! She wakes up to find herself surrounded by unfamiliar bushes. As she stumbles along, she's confronted by men holding guns, dressed like they're from a period drama! Is this the filming of a new drama?! The carefree An is rescued by a handsome young warrior on horseback...! Who is this guy?! I can totally support him! This overly optimistic high school girl finds her favorite idol in the Sengoku period!

(Source: Love Jossie, translated)