You must increase "heart levels" or relationship ratios with characters like Rosie, Lucy, and Mika to 100% to progress the plot.
Progress is sometimes gated by simple puzzles or the need to find specific items within the city. Storyline & Characters Descargar Happy Summer [v0.4.6] Tutorial [Гљltimo]
Activities include talking to characters in different rooms (kitchen, living room, bathroom), going to the beach, or visiting the local café. You must increase "heart levels" or relationship ratios