Shokushu Ningen ~Nurse no Itoko Hen~

Once every 97 years, the Tentacle Tree bears fruit.
One man ate that fruit to see if the legend was true.
Its transformative powers made him a human monster.
You are the hero! You are... Tentacleman!

This time you've gotten it in your head to stealthily
receive an examination from your sexy, beautiful cousin
who is a nurse at the central clinic.

[From DLsite English]