"Ocha-ken" is a slice-of-life anime series centered around anthropomorphic tea characters, each representing a different type of Japanese tea. The narrative unfolds in a whimsical world where these tea characters, known as the Ocha-ken, live together in a cozy house and engage in everyday activities. The main characters include Sencha, a cheerful and energetic green tea; Hōjicha, a calm and mature roasted tea; Matcha, a refined and elegant powdered tea; and Mugicha, a laid-back and easygoing barley tea. Each character embodies the unique qualities and flavors of their respective teas, which influence their personalities and interactions.

The plot revolves around the Ocha-ken's daily lives as they explore their world, interact with one another, and occasionally encounter other tea characters. The series emphasizes lighthearted, episodic storytelling, with each episode focusing on small, relatable events such as cooking, gardening, or celebrating seasonal festivals. The Ocha-ken often face minor challenges or misunderstandings, which they resolve through teamwork and mutual understanding, highlighting themes of friendship and cooperation.

The setting is a charming, idyllic environment filled with tea-related motifs, from tea fields to traditional Japanese tea utensils. The series incorporates educational elements, subtly teaching viewers about different types of tea, their preparation, and cultural significance. Despite its simplicity, the narrative maintains a gentle, soothing tone, making it suitable for audiences of all ages. The characters' interactions are warm and endearing, creating a sense of comfort and familiarity throughout the series.