Nope, it is this story what you said is on spot the heroine is indeed also a from another world cus she is reincarnated and her favorite is prince aquasteed, u probably red the novel and forgot about it
It’s not that exact plot, but there is this one! It’s about a girl reincarnated into the body of the game’s villainess, and she does whatever possible to ensure she gets to marry her favourite (side) character.
http://www.mangago.zone/read-manga/the_villainess_want_to_marry_a_commoner/
Could it be: "I’m a Villainous Daughter, so I’m going to keep the Last Boss"
http://www.mangago.zone/read-manga/i_m_a_villainous_daughter_so_i_m_going_to_keep_the_last_boss/
i'm really liking this one but does anyone know if there's a manga reeeally similar one to this?? because i can totally remember reading a manga where the prince breaks his engagement with the reincarnated mc (vilainess) to be with the heroine but after that happens the mc is asked in marriage by the prince of another kingdom and later it's revealed that the heroine is also from another world and her favorite character was the prince from another kingdom SORRy if it's confusing lol