Books like Onegai Teacher Book 1 by Shizuru Hayashiya

"The legendary novel of extraterrestrial war in an uncaring universe comes to comics, in a stunningly realized vision of Joe Haldeman's Vietnam War parable epic war story spanning relativistic space and time, The Forever War explores one soldier's experience as he is caught up in the brutal machinery of a war against an unknown and unknowable alien foe that reaches across the stars" -- The monumental Hugo and Nebula award winning SF classic-- Featuring a new introduction by John Scalzi The Earth's leaders have drawn a line in the interstellar sand--despite the fact that the fierce alien enemy they would oppose is inscrutable, unconquerable, and very far away. A reluctant conscript drafted into an elite Military unit, Private William Mandella has been propelled through space and time to fight in the distant thousand-year conflict; to perform his duties and do whatever it takes to survive the ordeal and return home. But "home" may be even more terrifying than battle, because, thanks to the time dilation caused by space travel, Mandella is aging months while the Earth he left behind is aging centuries...

Finding themselves in love despite their forced marriage, eighteen-year-old Earth boy Kei and his alien homeroom teacher Mizuho find their relationship tested by misunderstandings and jealousy.

Finding themselves in love despite their forced marriage, eighteen-year-old Earth boy Kei and his alien homeroom teacher Mizuho find their relationship tested by misunderstandings and jealousy.