Kinsei Tokkyuu

If you are chosen as the groom of the peerless beauty Venus, the splendor of this world will be yours to enjoy. However, not a single person has ever returned from boarding the special train that carries groom candidates, the Venus Express. In order to meet Venus, whom he fell in love with at first sight, Sabimaru drops out of high school and boards the Venus Express. With the help of Satetsu, a mysterious and unsociable man with exceptional skills, and Eustace, a handsome knight with a natural appetite, Sabimaru's incredible journey begins. A thrilling, full-scale adventure begins!!

(Source: Shinshokan, translated)