While previous studies on self-regulated learning (SRL) in the second and foreign language (henceforth L2) have accumulated numerous empirical findings showing that variables related to SRL have a significant impact on L2 learning, the majority of these studies have been conducted in limited contexts such as Hong Kong and China and have predominantly focused on specific skills such as vocabulary and writing. In order to broaden the understanding of the relationship between SRL and L2 learning across different learning skills and contexts, the current research aimed to examine the relationship between SRL and English proficiency among first-year university students (n = 47) from an English-related major at a Japanese private university. Our research used a questionnaire to measure SRL variables, including self-regulation, grit, and motivational variables (i.e., self-efficacy, intrinsic value, and growth mindset), and TOEFL test scores to measure English proficiency. The results showed that although Bayesian Kendall's tau correlation analysis provided some support for the relationships between certain aspects of self-regulation, such as awareness, goal setting and management, and emotion control, and their relationships with self-efficacy and grit, no correlations was found for most variables. These results contrast with findings from some previous studies conducted in non-Japanese contexts. The inconsistent results across studies may be attributed to contextual differences. Based on these findings, implications for future L2 SRL research are discussed and considered.