At the time of the murder, Yamaguchi had a note in his pocket that read:
You, Inejirō Asanuma, are planning to turn Japan red [i.e. communist]. Although I bear no grudge against you as an individual, for the stances you have taken in your role as leader of the Socialist Party, for the outrageous statement you made when you visited China, and for the responsibility you bear for the intrusion into the National Diet,[note 2] I cannot grant you forgiveness. I shall hereby become the instrument that brings down heaven's judgment upon you.
Day 12 of the 10th month of the 2,620th year of imperial rule,[note 3] Otoya Yamaguchi
Note 2: This is a reference to the "June 15th Incident" of 15 June 1960, when leftist protesters stormed the National Diet compound to protest the Security Treaty
Note 3: 12 October 1960 in the Gregorian calendar.
From wikipedia:
You, Inejirō Asanuma, are planning to turn Japan red [i.e. communist]. Although I bear no grudge against you as an individual, for the stances you have taken in your role as leader of the Socialist Party, for the outrageous statement you made when you visited China, and for the responsibility you bear for the intrusion into the National Diet,[note 2] I cannot grant you forgiveness. I shall hereby become the instrument that brings down heaven's judgment upon you. Day 12 of the 10th month of the 2,620th year of imperial rule,[note 3] Otoya Yamaguchi
Note 2: This is a reference to the "June 15th Incident" of 15 June 1960, when leftist protesters stormed the National Diet compound to protest the Security Treaty
Note 3: 12 October 1960 in the Gregorian calendar.