Reborn as the Strongest Guide, I Have the Cold Commander Begging for My Help

[Sentinel and Guide + beast world + one-on-one romance + transmigration + male lead is sexually inexperienced + strong heroine + marriage before love] The most powerful mage on a magical continent lost a battle against the Demon King and transmigrated 3,000 years into the future, into the body of Ning Su, a good-for-nothing F-rank Guide in the interstellar federation. A political conspiracy forced her to marry an SSS-rank commander. Ning Su only wanted to earn enough FUCK YOU MONEY as quickly as possible and get back to training as a great mage. Who knew she would end up shouldering the survival and evolution of humanity, as humans began evolving into beastfolk! The heroine takes the long view. If no one bothers her, she's all smiles; if they do, they'll learn they've picked a fight with someone who won't back down. The male lead seems cold and quick-tempered, with overwhelming combat prowess, but underneath he's a tsundere who just wants to cuddle up with her.