Different brand, slightly bigger than Lego
Taking an image from the linked course site and using Google Image Search for reverse image searching, then applying a layer of Google Translate to make sense of the exclusively Japanese results has convinced me that this type of building system is only used in this robotics course in Japan. Nonetheless, the institution seems to sell the sets as standalone products for 28,500 yen, unless I misunderstand the translation results somehow:

At Human Academy's Robot Class, we will increase the number of kits that will be added when advancing the course, based on the standard kit (* 1) that you purchase when you join.
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(* 1) 28,500 yen 〚tax excluded〛