[Reviewed at Chapter 49]
This isn't a typical cliché isekai - MC's old memories are merged into the new body, but he strongly identifies with his new body/identity and not his old one. Unfortunately, the story is full of annoying characters and unrealistic plot developments, which makes it annoying to read.
The biggest issue I have with this manga is how spineless and stupid all the characters are. For instance, the MC is accused of throwing a princess off a cliff, but even though the princess herself says that the MC didn't do it, no one believes her - and what's more, she doesn't do much to stand up for him, even though she saved her life, at the risk of his own life. This sort of stuff goes on constantly.
Later, the MC runs into a person who also potentially transmigrated from Japan, and although he couldn't have had a chance to meet this person, he completely ignored them and just moved on. I mean, wouldn't you want to meet that person and find out how they came to this world etc?
Then there's the the issue of the characters, including the MC, not being honest with their feelings, and as a result, cause missed connections, unnecessary heartache and misunderstandings etc.
Overall, there's a lot of potential here, as this isn't an overly-clichéd isekai, but sadly the unrealistic and annoying characters, plus the excessive harem-isation makes this a very annoying manage to read.