Dude, I wish; it's so cute. But, here is something with the concept of being adopted from hellish life of neglect into a sweet family ready to spoil them.
*Beware of the Brothers: Fluff comes later, heartache and misunderstandings come first. But, it makes the fluff much more worth it.
*The Princess in the Dumpster: Neglect before going into royal family only a few chapters, but worth the wait.
*Kamitachi ni Hirowareta Otoko: lighthearted isekai; very cute.
*Eiyuu Densetsu: Sen no kiseki (The Legend of Heroes: The Trail of Cold Steel); heard about it haven't read it myself, looks like it has heavy worldbuilding though.
*I am a Child of this House: So cute- definitely similar but little bit of drama and triggers.
*The Twin Siblings' New Life: One of my new favorites, so endearing and heartrending. Isekai full of great fluff potential.
*Death is the Only Ending for the Villainess: heartrending, isekai. Past plays an important role to the MC's mindset.
The next list is about manga I think are similar to Marimashita Iruma in terms of humor or concept of keeping secrets about themselves. Note: at least one character in each has Daddy issues.
*Beezlebub: The humor is rich in this one, very action packed and has to do with Demons, Demon Lords, and Demon world eventually.
*Ao no Exorcist: The humor is good but the drama gets better; also action packed and heartrending. All about sons of Satan and living with who you are and what you want to become.
*Classroom of the Elite: Modern setting, very mysterious and secretive. Starts off feelings more like Baka no Test, Assassination Classroom, and Angel Beats.
Ahh, thank you!!! I'm gonna read them all :") !!! If I find some mangas like Marimashita! Iruma-kun I'm going to tell you too!!ヾ(❀╹◡╹)ﾉ~
Hello, do you guys know any manga like http://www.mangago.zone/read-manga/mairimashita_iruma_kun/