Kaede Saitō is a 16-year-old high school student born January 16, 1997, standing 164 cm tall and weighing 53 kg. She possesses long black hair reaching her waist and wears glasses. Her well-proportioned figure contrasts with her preference for simple, comfortable home attire like sports bras and shorts, prompting friends to remark she's "wasting a good figure" through fashion indifference. This trait leads to humorous moments, such as discovering her correct bra size is unexpectedly large during a shopping trip.

She first encounters protagonist Aoi Yukimura in a mountain gear store, offering sleeping bag advice and becoming Aoi's first new friend beyond childhood companion Hinata Kuraue. Academically capable but unmotivated, Kaede achieves top scores like class top-ten rankings only under pressure. She frequently relies on middle schooler Kokona Aoba for homework help and receives strict tutoring from classmate Yuuka Sasahara. She funds her mountaineering hobby through part-time work.

Initially a solo hiker, Kaede gradually integrates into group hikes with Aoi, Hinata, and their friends after meeting Aoi. She serves as their knowledgeable mentor, sharing extensive hiking experience while deliberately avoiding formal clubs to maintain independence. Her athleticism is undercut by an inability to swim and a fear of using knives during outdoor cooking.

Her development involves evolving from a solitary enthusiast to valuing companionship on trails, yet retaining her core laziness in non-mountaineering contexts and ongoing fashion apathy. Her relationships define her role as a reliable "mountain teacher" to Aoi and Hinata, her academic dependence on Kokona and Yuuka, and her consistent rejection of hiking club invitations in favor of informal outings.