Jinrui wo Metsubou sasete wa Ikemasen

Also known as: 人類を滅亡させてはいけません, Don't destroy humanity

by Kyuu Takahata, Yuuji Kaba

On his way home from work, the 26 year old salaryman, Kawakita Osamu, encounters an alien named Lilin. She and her species plan on invading the earth but she ended up getting stranded on this planet. Can Osamu raise her to become a kind-hearted kid before her species eradicates humanity in five years? Note: Includes 3 extra chapters.