In the diary he wrote from 1655 to his death, called "Motohiro koki," Motohiro regarded with humor the bloodshed inflicted on (Yoshinaka) KIRA by Naganori ASANO during the Genroku Ako Incident, as 'what a unusual occurrence it is,' and wrote about the reaction of Emperor Higashiyama, who heard about the incident, as 'the Emperor said that it is a funny thing.'
また1655年から死去まで書き続けている日記を『基熈公記』といい、この中で元禄赤穂事件についての記述で浅野長矩の吉良への刃傷についての感想を基熈は「珍事々々」と面白げに書いており、また事件を聞いた東山天皇の様子について「御喜悦の旨、仰せ下し了んぬ」と記している。