Hating tsundere is good, even if you know they are they can be dere, go honest or go home.
The manga cover are a lie, but can't sell stuff with old farts there.
Try Amazon! Here are links to the physical (not Kindle) versions:
Volume 1: https://www.amazon.co.jp/異世界おじさん-1-MFC-殆ど死んでいる/dp/4040653688/
Volume 2: https://www.amazon.co.jp/異世界おじさん-2-MFC-殆ど死んでいる/dp/4040657071/