"Stringendo - Angel-tachi no Private Lesson" is a short-form anime series that revolves around the lives of four angelic beings—Harp, Lyra, Horn, and Lute—who are tasked with guiding and teaching humans through music. Each episode focuses on their interactions with humans, often involving lighthearted and comedic situations as they attempt to impart lessons or solve problems using their musical abilities. The angels are portrayed as whimsical and slightly mischievous, often struggling to fully understand human emotions and behaviors, which leads to humorous misunderstandings.

The narrative is episodic, with each installment presenting a self-contained story centered on a specific human character or scenario. The angels use their unique musical talents to inspire, comfort, or teach their human charges, often blending magical elements with everyday life. Despite their divine nature, the angels are not infallible, and their efforts sometimes result in unintended consequences, adding a layer of charm and relatability to their characters.

Harp, the leader of the group, is responsible and earnest but occasionally overconfident. Lyra is gentle and empathetic, often acting as the emotional anchor of the group. Horn is energetic and impulsive, frequently causing chaos with her exuberance, while Lute is quiet and introspective, offering thoughtful insights. Together, they form a dynamic ensemble that balances humor and heartwarming moments.

The series emphasizes themes of growth, understanding, and the transformative power of music, presenting these ideas in a lighthearted and accessible manner. While the tone is predominantly comedic, there are occasional moments of sincerity that highlight the angels' genuine desire to help humanity. The episodic structure allows for a variety of scenarios, ranging from personal struggles to broader societal issues, all addressed through the lens of the angels' musical interventions.