Today, the seven-day training of Guren’s anus begins… The freedom of my limbs is taken away, and the tentacle implements its technique by violating my anus… At first it made my anus tighten, it repeatedly teased my anus with steadily more plump and thick ones, working to develop me into a ‘latrine’ for lewd cum… The blush doesn’t deepen as the sphincter is stretched by Guren’s burly tentacle-penis, the sexual feelings done to exhaustion as the intestinal walls are stretched and rubbed… My anus too, in order for it to become a completely different creature, close the soft entrance, in order to feel the thick tentacle-penis… I indulged in the pleasure caused by it wriggling in my anus… For my first time… I vowed in my heart that I would resist and would absolutely not break from the ‘anal training’… Due to it persistently tormenting my anus, I won’t give in to this tentacle-penis… It played with my anus in various ways, raping it, giving love to Guren… It'll work until my heart has been 'trained'... I... For the 'anal training'... I will... win...
(Translation and Pronoun Usage (i.e., who is talking, and who are he/she/they referring to?) Rather Unsure)