Thank goodness the immortality drug is still incomplete I hope this drug is never completed, it would be horrible if they don't die in the end (Rentaro with 100 years or so)
I mean there is an anime that it's about this exact plot:
Bludgeoning Angel Dokuro-chan tells the story of 14-year-old junior high schooler Sakura Kusakabe, who twenty years in the future develops a technology that causes all women to stop physically aging after they reach twelve years old in an attempt to create a "Lolicon's World". However, this act accidentally creates immortality amongst humans, thus offending God. Dokuro Mitsukai, a member of an order of assassin angels that are called Lulutie, has been sent from the future to kill him.