Language play is claimed to be beneficial for second language learning in many studies, and Harada (2005) offers various language play activities which can be utilized in English teaching in Japan. However, sufficient theoretical consideration is missing in these studies. The author describes a short lesson based on language play and analyzes conversations of three participants (female junior high school students) to investigate the characteristics of leaners’ behavior when they engage in language play. The result shows that in language play focused lesson, learners can focus on language forms and meanings, actively engage in learning, and make use of previously learned language knowledge in creative ways.