The supporting character's harem is very normal - Chapter 358 Sorry… Lathel… I’m really sorry.

After being given up on by his family because his dantian was destroyed, Soh Woonhwi was kidnapped by the Blood Cult and lived as a third-rate spy.

One day, he died while being used to find a legendary sword immortal’s secret records. However, he returned to the day he was kidnapped ten years ago and obtained a mysterious ability that allowed him to hear the voice of swords.

[Ding!][Acquired the Dragon Queen's Legacy][Acquired the Elf Queen's Legacy][You have awakened the Strongest System]“It's real...! Isekai is real!”******Drax is a laid-back, calm and collected highschool student who accidentally loses his life on Earth and, in turn, has his soul is summoned into the body of a baby in another world, one where mana and magic abound.Blessed with a Dragon Legacy, an Elven Legacy and the love of two mummies, Drax decides to enjoy this second life being free and lively freely, not conforming himself to any world system.“The only way to be the freest person is to also be the strongest person,” Queen Freya said to him.And so begins Drax's journey to become the strongest and freest!

This is a story about the protagonist getting the system, going crazy in the biochemical apocalypse, producing aircraft and tanks, destroying zombies, saving good people and killing bad people.

- Description from novelbuddy

As the number one pill alchemist of the immortal world, Mu Chen had always believed that it was because he had single-mindedly focused on concocting pills that led to him to neglect disciplining his disciple. Which in turn, caused his disciple to be led astray by the seduction of devil cultivation, leading to the three realms to fall to disaster. After his rebirth, Mu Chen resolved to properly teach his disciple, give him the very best resources, earnestly love him, carry him close to his heart, teach him by way of example, and didn’t let him grow corrupt.

Sure enough, his disciple became more and more “intimate”. Every day his disciple even crawled into his bed, rubbing against his chest and clinging to his thigh. It was just that his expression isn’t exactly quite right……

- Description from novelupdates