"Sweetness & Lightning" centers on Kohei Inuzuka, a single father and high school teacher, who struggles to balance his responsibilities as a parent and his grief following the death of his wife. Left to care for his young daughter, Tsumugi, Kohei finds himself overwhelmed by the challenges of cooking nutritious meals, as he lacks culinary skills. Their daily routine consists of convenience store meals, which leaves Tsumugi longing for homemade food.

The story takes a turn when one of Kohei’s students, Kotori Iida, invites the pair to her family’s restaurant, which has been closed since her mother’s passing. Kotori, who is passionate about cooking but lacks confidence, offers to teach Kohei how to cook in exchange for their company. The trio begins spending time together in the restaurant’s kitchen, where they prepare simple, heartfelt meals. Through this shared experience, Kohei and Tsumugi gradually rediscover the joy of homemade food, while Kotori finds purpose and companionship in guiding them.

The narrative explores themes of family, healing, and the emotional connections forged through food. Kohei’s journey as a father is central, as he learns to navigate his grief and provide for Tsumugi in meaningful ways. Tsumugi, with her innocent curiosity and love for food, serves as a catalyst for the group’s growth. Kotori’s role as a mentor and friend bridges the gap between her own loneliness and the Inuzukas’ need for support. The series emphasizes the importance of community and the small, everyday moments that bring people together, all framed within the context of cooking and sharing meals.