It seems you're looking for a guide or information on the manga (often shortened to Taishou Itsuwari Bridal or Taisho Fake Bridal ). This is a historical romance manga set in the Taishō era (1912–1926) of Japan.
The groom is a (gunpuku = military uniform) — cold, calculating, but handsome and powerful. He knows she’s a fake but agrees to the engagement for political or family reasons.