Here is an analysis of the manga in my view!
Neither the Ruka situation, nor Kazuya coming clean has been resolved this chapter.
This is a clear message by the author, of how he feels about CBT culture, and how he himself feels about the topic.
He himself does not only see the value of the moment, where the COCK and BALLS are crushed by a rock, but instead also values the moments leading up to the act, ergo the foreplay.
This falls obvious to the reader, by the fact that the manga shows various ups and downs leading up to a potential confession, but never the actual confession.
Such a progression is also found in the sexual act of "EDGING", where a individual or a pair stimulates a COCK up until the very last moment before a climax occurs,
upon which a cancelation of said stimulation or stimuli is stopped immediately to stop a upcomming climax.
The author shows a clear acquaintanceship with this phenomenon mentioned above, and draws a clear allegory to the act of "EDGING" and the confession of KAZUYA to MIZUHARA.
He critiques the current day procedure of CBT as it is portrayed in modern society, as it merely portrays the act of CRUSHING ones COCK with a stone to receive MAXIMUM PAIN.
The author of this manga sends a message to his readers, which show his ideal way of CBT, packed into the format of a romance comedy manga, to conceal his true intention to the true CBT connisseurs.
Said ideal way of CBT being a process of at least 180 ch. long foreplay of teasing the act of the crushing, whilist not delivering.