"Ii Koto ni Shiyo" is a manga series that revolves around the life of a young man named Shunpei, who, after a series of personal setbacks, decides to make a conscious effort to improve his life by doing good deeds. The narrative begins with Shunpei losing his job and his girlfriend on the same day, leaving him in a state of despair. In an attempt to turn his life around, he adopts a philosophy of performing one good deed every day, believing that this will bring positive changes to his life.

As Shunpei embarks on this journey, the story explores the various ways in which his actions impact those around him. Each chapter typically focuses on a specific good deed, ranging from helping a stranger in need to standing up for a coworker facing unfair treatment. These acts of kindness often lead to unexpected consequences, both positive and negative, highlighting the complexities of human interactions and the ripple effects of even small gestures.

The main characters include Shunpei, who serves as the protagonist, and a supporting cast that includes his friends, family, and acquaintances who are affected by his actions. Notable among these is his childhood friend, Yuki, who provides emotional support and often offers a different perspective on Shunpei's endeavors. Another key character is his boss, Mr. Tanaka, who initially views Shunpei's efforts with skepticism but gradually comes to appreciate his sincerity.

The plot progresses through a series of episodic encounters, each contributing to Shunpei's personal growth and the development of his relationships. The narrative maintains a balance between light-hearted moments and more serious reflections on the challenges of maintaining a positive outlook in the face of adversity. Themes of perseverance, empathy, and the impact of individual actions on the broader community are central to the story.

Throughout the series, Shunpei's commitment to doing good deeds is tested by various obstacles, including misunderstandings, personal doubts, and external pressures. However, his determination to stay true to his philosophy drives the narrative forward, culminating in a resolution that underscores the value of kindness and the potential for personal transformation through altruism. The series concludes with Shunpei reflecting on his journey and the lessons he has learned, leaving readers with a sense of closure and a reminder of the importance of striving to make a positive difference in the world.