Inu x Boku SS, Orange Recommendations
SPOILER: Very similar concepts about traveling back in time to save lives.
There's a very important concept in both manga (can't say what it is, cuz spoiler; so read it and find out), besides that, there are characters that you'll end up loving. And there is romance and lots and lots of feels (like a lot, enough feels to break your heart ten times) in both. Also, they both have amazing art, the plot is fantastic and characters are relatively similar-ish. And the bonds that the characters all have with each other is quite similar, too.
Also, they both have animes, too. So, after reading it and riding the feel train, you can watch it and ride