Studies focused on motivation to learn languages other than English or more than 1 language simultaneously have been gaining attention in recent years. However, there are far fewer than those related to second language (L2) English learning. To fill this gap, this article explores the evolving motivation of 2 Japanese students who spent 1 academic year learning both English and Chinese on a study-abroad program in Taiwan. The data consist of semistructured interviews conducted before and during the program along with motivation graphs drawn by the students. The interviews were transcribed, coded, and categorized. The L2 motivational self system and the concept of the ideal multilingual self are used as frameworks to capture the complex experience of learning multiple languages simultaneously. To capture the dynamic and complex nature of motivation, this article also applies three different timescales (microgenetic, mesogenetic, and ontogenetic) to analyze learners' experiences. The results show how ideal and ought-to second- and third-language selves emerged along with an ideal multilingual self in 1 of the students while abroad. The interviews also revealed multiple learning experiences and struggles in maintaining balance, with both languages competing for limited cognitive resources and study time.