Our Universe tells the story of Woo Hyun Jin (Roh Jeong Eui) and Sun Tae Hyung (Bae In Hyuk), two young adults whose lives are thrown into turmoil after an unexpected tragedy leaves them responsible for raising their nephew, Sun Woo Joo (Park Yu Ho). What begins as an uneasy relationship gradually turns into a shared journey of responsibility, healing, and growth.

The drama opens with Hyun Jin and Tae Hyung discovering that they are about to become in-laws. A family dinner meant to celebrate an upcoming marriage takes an awkward turn when Tae Hyung suddenly appears, revealing unresolved tension with his older brother. Adding to the discomfort, Hyun Jin and Tae Hyung realize they have already crossed paths before, having clashed over a lamp in an earlier encounter that ended on poor terms.

Three years later, the story takes a dramatic turn when Hyun Jin’s sister and brother-in-law pass away in a car accident, leaving their young son without a guardian. The tragedy reunites Hyun Jin and Tae Hyung under painful circumstances, forcing them to confront a responsibility neither had anticipated nor felt ready to accept.

As the question of Woo Joo’s future arises, Tae Hyung initially distances himself due to his strained relationship with the family. Ultimately, it is Hyun Jin who steps forward to take on the role of guardian. Despite the overwhelming situation, Woo Joo’s presence brings moments of warmth and light into an otherwise devastating period.

Circumstances soon lead Tae Hyung to temporarily move in with Hyun Jin after delays in his home renovation leave him without a place to stay. With clear conditions regarding rent and childcare, the two begin an uneasy experiment in co-parenting. While both struggle with their own uncertainties, caring for Woo Joo gradually becomes the bridge that helps them find common ground.
The premiere concludes on a hopeful note as Hyun Jin finally lands her long-awaited job, offering a sense of stability for the future. At the same time, the appearance of a man at her workplace who seems connected to her past introduces a quiet mystery, hinting at new developments ahead.
Through its premiere episodes, Our Universe establishes itself as a gentle yet honest portrayal of adulthood, loss, and the imperfect process of learning how to move forward together.