Nichijou follows the everyday lives of various people in the town of Tokisadame,[4] centering on the energetic Yūko Aioi, the bright and cheerful Mio Naganohara, the quiet and deadpan Mai Minakami, the anxious android Nano Shinonome, her young creator the Professor, and a talking black cat named Sakamoto, along with an ensemble cast of characters. Random and/or outlandish events regularly occur throughout the series, mainly through the mundane situations each character goes through.
In the anime series, Nano receives the most prominent story arc out of all the characters; the first half of Nichijou involves her desire to become a student in high school, while the second half deals with her fear of being exposed as a robot while at school. Vignettes which are mostly unrelated to the main focus of the series are placed throughout each episode, some of them adapted from another manga by Arawi, Helvetica Standard.