For beginners: His dad suddenly becomes an immortal, and Xi Feng becomes an immortal's second-generation kid. To fulfill his otaku son's wish, his father sends him to the anime world, where he happily spends his days chasing girls.
(P.S. Although the title is a bit improper, the story is quite proper: it really is about chasing girls, just look at that earnest expression. Also, the word "beast" comes from the saying about whether one should be a beast or worse than one, and does not imply any particularly depraved content.)
For the literary-minded: When the flower blooms and is ready to be plucked, pluck it; do not wait until there are no flowers left, then break off an empty branch.
The road to a harem is full of hardship and thorns. The deeper the love, the more easily the lovers hurt each other. There is joy and there are tears. Tell me, what is love in this world, that it makes people vow to follow each other in life and death?
