The purpose of this study was to look at the Waseda-Meiji rugby game a prominent college sporting event that draws huge crowds of spectators-as a case study to examine the factors that affected those spectators in deciding to go to the game and examine the differences in those factors for several categories (e.g., gender, age, affiliation). As a result of an exploratory factor analysis (n=236) conducted using a Spectator Decision-Making Inventory (SDMI) supplemented and modified based on a preliminary study, a total of 13 items grouped into three factors (both internal and external) were extracted: Game Promotion and Social Element represents the ticket price, events held at the venue, having friends and acquaintances playing the game, and the presence of accompanying individual(s); Home Team represents the home team's league standing, win/loss record, and superstar(s); and Opposing Team represents the opposing team's superstar(s) and overall performance. After testing the differences in factors by category (gender, age, affiliation, and experience going to the game), differences were found in multiple categories, suggesting that it is necessary to approach each category differently. This indicates the need to continuously roll out measures to stimulate the Game Promotion and Social Element factor, which is effective for those in their teens and 20s, current college students, and females, in addition to strengthening the Home Team factor, which is effective in attracting Waseda alumni, those in their 40s and 50s (the largest age group), and spectators who have been to the game in the past.