Children’s early age is the golden age when about a hundred billion brain cells are ready to receive stimulation to increase optimal intelligence. Intelligence at the age of 18 is 50% formed at the age of 0-4 years. In this phase, children experience unique development, including physical, cognitive, social-emotional, and so on, which needs to be stimulated according to their growth. This stimulation can be provided with play activities. Repetitive play in childhood phase will stick in the memory for a long time, so it is necessary to provide playing media that can accommodate children’s development. The example is busy book that includes various playing activities to train fine motor skills, imagination, and problem solving. However, busy book products that have been widely marketed generally focus on independent use so that children are not encouraged to interact with others. There is also pretend play that trains social-emotional skills, yet the activities still need to be developed into interactive ones like busy books. Considering the above, the design of educational toys combining busy book and pretend play to explore children’s inner development is carried out. The research is based on data collection methods including literature, interviews, and observations. Afterwards, various topics such as user analysis, market, environment, educational elements, product specifications, production, and business were analyzed. This then led to the concept of a thematic play series with interactive activities that can enhance aspects of child development.