I'm The Tentacle Monster You Picked Up

Love Island. A place where "monsters" and "humans" live together in peace. The human protagonist, Haruyo, lovingly nurtures a monster, and that monsters grows quickly with that love. He found the monster on the beach one day, and naming it Rita, they begin living together and deepening their bond. Having been filled with the love of her master, eventually Rita "grows" into something new---- However, the result of her "growth" is beyond Haruyo's expectations... Before him towers the form of a large and erotic girl...! Having become a big strong monster girl who just loooooves her master... she begins to "repay the favor" with some totally and utterly one-sided reverse r\*pe...!! Yayyyy...!!!! Goodbye dignity...!!!!!!! (Source: Dlsite translated)