The song "Lullaby" by UMI tells the story of two individuals in a relationship where one person is hurting and struggling to communicate their emotions. The narrator, UMI, expresses her desire to understand and help her partner, asking why they won't let her in and understand their pain. In the song, UMI offers to sing her partner a lullaby, hoping that this gesture will make them feel more comfortable and open up to her. By singing a lullaby, UMI wants to create a soothing and calming atmosphere that will enable her partner to share their feelings with her. Yeek, who is featured in the song, emphasizes the difficulty of expressing emotions, mentioning that he doesn't want to acknowledge his emotions but gets emotional at night when he's alone. Throughout the song, UMI continues to plead with her partner to let her in and be vulnerable with her. She expresses her concern for their well-being by mentioning that she has bought a bouquet, symbolizing her efforts to bring some beauty and positivity into their lives. UMI wonders when her partner will try to be okay and find healing and happiness. Overall, "Lullaby" is a heartfelt plea for emotional connection and understanding in a troubled relationship. It explores the challenges of communication and the desire to help someone heal and feel better.