In second or foreign language (SFL) education, oral corrective feedback (OCF) is widely used to individually correct students’ erroneous utterances during classroom hours. However, students cannot have sufficient opportunities for oral production and personalized feedback during classroom hours if a class is large-scale with many students. This paper addresses the lack of OCF opportunities in a large-scale class, assuming the causes to be the severe time constraints and the teachers’ labor intensiveness in examining students’ utterances and generating OCF. This research proposes using computer-mediated feedback (CMF) outside classroom hours to complement OCF in an online, semiautomated, and scalable fashion. This paper implements Oral Repetition Practice (ORP) Gym to provide students with sufficient opportunities for speaking practice through two types of CMFs; Hybrid Recast to enhance the recognition of errors and Explicit Error Correction to make errors detectable and correctable. Online External Assistant (OEA) is a mechanism used to increase the amount and quality of feedback by distributing the workload for scoring and generating CMF. The evaluation was conducted as a classroom observational study by introducing ORP Gym to a spoken Japanese SFL basics course with 55 students at an Indian university. Compared with the students who did not utilize ORP Gym, those who utilized ORP Gym performed more ORP and exhibited significant score improvement in the posttest. This research contributes to enabling CMF in large-scale SFL classes and empirically and statistically proving the improvement of the learning effect, including uptake and repair, by CMF using ORP Gym and an OEA. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.