Hotline callers do not always have suicidal ideation and previous studies have noted that the rate of such callers is limited. Crisis hotline counselors must be able to identify high-risk callers in order to provide appropriate support. This study investigated the characteristics of Japanese crisis hotline callers in 2012 (N = 541,694) and is the first to analyze crisis hotline data for all parts of Japan over 1 year. About 14% of the callers had suicidal ideation and 6% had a history of attempted suicide. The odds ratio for suicidal ideation among those with a history of attempted suicide was 15.5. The suicidal ideation rate was much smaller compared to previous studies in other countries. There is a psychological barrier that must be broken for high-risk people to use support hotlines. In addition, attempted suicide is a strong exclusive predisposing factor for death due to suicide; therefore, counselors should pay careful attention to callers with a history of attempted suicide. The characteristics of Japanese crisis hotline callers and the features of suicidal ideation revealed in the present study are expected to be useful in developing telephone crisis hotline strategies.