This research proposes a system to support Japanese vocabulary learning for L2 learners of Japanese by integrating object recognition technology and a thesaurus database. Vocabulary learning is the foundation of L2 learning, but traditional translation-based learning is still the mainstream. The proposed method is based on the hypothesis of the effectiveness of associating visuals and synonyms in vocabulary learning. The system combines YOLOv7 and WordNet Japanese, called PICSU (PICture-based Synonyms Understanding), to provide a unique and context-rich vocabulary learning experience. Preliminary experiment results from international graduate students as participants implied improved retention and engagement compared to traditional flashcard-based learning. This article outlines the proposed approach and highlights the potential for integrating intelligent information processing technology with vocabulary learning practice.