During his 80th birthday, Watari Eiji has a heart attack. On his deathbed, he desperately wishes to fulfill his one wish in his next life. Instead of reincarnating, he spontaneously becomes his younger self.

A "scientific" perverted manga with a lot of tentacles. Komaba Haruki is a high school boy who has two eccentric girl friends: Hizuki Ayana and Kuze Airi. Ayana is half-dog and Airi is half-cyborg. Haruki gets involved in ecchi troubles caused by the two.
(Source: MAL news)

Suddenly transported to another world. Being called the ‘Suitable One’, with the world’s strongest power “Holy Sword”. He thought he would use that power to make a great impact in this new world. However, in this alternate world there are "inhumans"; Monsters that oppress the lands. Questioning his own convictions, he asked, is this correct? Who should he use this power for? This is the beginning of an Isekai battle fantasy!

(Source: MU, edited)