Research on second language (L2) pronoun use in null-argument languages has traditionally focused on whether or not a speaker's first language (L1) also allows null pronouns. However, recent studies have pointed out that it is equally important to consider the specific linguistic properties of overt pronouns in the L1 and L2, which may differ even across two null-argument languages. This study investigates the interpretation and processing of overt pronouns in Japanese by speakers whose L1 (English) and L2 (Japanese) differ not only in whether they allow null arguments, but also in the relative involvement of structural and pragmatic constraints on overt pronoun interpretation. This combination of languages is particularly interesting because English and Japanese overt third-person subject pronouns can be considered at extreme ends of a spectrum: in English they are largely structurally constrained and show a consistent preference for a local subject antecedent, while in Japanese they are loosely constrained by pragmatic factors and show no consistent interpretation preference. Both interpretation and eye-tracking data is recorded, with results suggesting that the unique nature of overt pronouns in Japanese, including their rarity in the input, leads to partial knowledge of them on the lexical level rather than implicating the larger syntactic system or syntax-pragmatics interface.