"Marmalade Boy Little" is a spin-off of the original "Marmalade Boy" series, focusing on the lives of the younger siblings of the main characters from the parent story. The narrative centers on Miwa Kinoshita and Arimi Suzuki, who are navigating the complexities of adolescence, friendship, and budding romantic feelings. Miwa, the younger sister of Yuu Matsuura, is a cheerful and energetic middle school student, while Arimi, the younger brother of Miki Koishikawa, is more reserved and introspective.

The story begins with Miwa and Arimi meeting at school, where their contrasting personalities initially lead to misunderstandings and minor conflicts. However, as they spend more time together, they develop a close friendship. The series explores their daily lives, including school activities, family dynamics, and interactions with their peers. Miwa’s outgoing nature often pushes Arimi out of his comfort zone, while Arimi’s thoughtfulness helps Miwa see things from a different perspective.

Romantic tension gradually builds between the two as they navigate their feelings for each other. Miwa’s straightforward approach to emotions contrasts with Arimi’s hesitance, creating a dynamic that drives much of the narrative. The series also delves into their relationships with other characters, such as classmates and family members, adding depth to their individual growth and the evolving bond between them.

Themes of self-discovery, communication, and the challenges of young love are central to the story. Miwa and Arimi’s journey reflects the struggles and joys of adolescence, as they learn to understand themselves and each other. The series maintains a lighthearted tone while addressing the emotional complexities of its characters, making it a relatable and engaging continuation of the "Marmalade Boy" universe.