"Hōkago NyanNyan" centers on the daily lives of a group of high school girls who form a club dedicated to caring for stray cats. The protagonist, Yui, is a kind-hearted and responsible student who discovers a stray cat near her school. After bringing it to the attention of her classmates, they decide to create the "NyanNyan Club" to provide shelter, food, and medical care for the growing number of stray cats in their neighborhood. The club members include Aoi, a pragmatic and resourceful girl; Miku, a shy but passionate animal lover; and Rina, a cheerful and energetic student who often lightens the mood with her humor.

The narrative unfolds through episodic chapters, each focusing on the challenges and joys of caring for the cats. The girls face various obstacles, such as finding funding for their club, dealing with skeptical school administrators, and addressing the health issues of the cats they rescue. Their efforts often require creativity and teamwork, showcasing their growth as individuals and as a group. The story also explores themes of responsibility, compassion, and the importance of community, as the girls work to raise awareness about animal welfare and inspire others to take action.

Interpersonal dynamics play a significant role in the series, with the club members navigating their friendships and personal struggles alongside their shared mission. Yui’s leadership and determination often serve as the driving force behind the club’s initiatives, while Aoi’s practicality ensures their plans are feasible. Miku’s deep empathy for the cats provides emotional depth to the story, and Rina’s humor and optimism balance the more serious moments. The series also introduces secondary characters, such as supportive teachers and skeptical peers, who add complexity to the narrative and highlight the broader impact of the club’s work.

The cats themselves are central to the story, each with distinct personalities and backstories that endear them to the readers. Their interactions with the girls often serve as a source of humor, warmth, and occasional drama, reinforcing the bond between humans and animals. The manga’s tone is predominantly lighthearted, with moments of emotional weight that underscore the challenges of animal rescue and the rewards of making a difference. Through its focus on the NyanNyan Club’s endeavors, "Hōkago NyanNyan" offers a heartfelt exploration of friendship, perseverance, and the impact of small acts of kindness.