lol: After being blessed by the Happy Demon, I became the harem king

Tragic news has arrived from Runeterra: the female heroes have all ascended to the planet of happiness.
The Devil of Joy bestows his blessing, granting Fahn the power to summon wind and rain and control lightning. In Zaun, he encounters a monster of unparalleled strength. Jinx fights with all her might but is powerless against it; a single injection causes her blood to thicken like petroleum jelly, her heart pounding and her eyes sparkling with hearts.
Piltover, enraged, launched a righteous attack, but Caitlyn betrayed them by drinking a dose of euphoria. Dopamine connected her nerves, causing her to go into overdrive and lose control on the spot. The product was too pure and the effect too strong, leaving her weak and ate a train-style bento in a small room.
Noxus was amazed and secretly learned the formula for the powerful drug. However, the experiment by the foolish beauty resulted in an accident where the pleasure factor spread like a plague, and the entire country was affected without exception. Meanwhile, the Katarina sisters enjoyed a blissful life.
Out of curiosity, Lux accidentally fell into the trap, transforming into a Demacian water sprite. She dragged Fiora into her life, insisting on being her sister, and enthusiastically recommended the idea to Sona, then pulled her underwater in the bright sunshine—you're the next one to be dragged down!
Freljord unified the ice plains, and the three sisters joined forces to fight the demons. Their unity was invincible, but unfortunately, Fane's power was too great, so they temporarily retreated and suffered a crushing defeat, leaving them with nothing but sacrifice.
Ionia used gentleness to overcome strength, and Venerable Karma offered himself to the tiger. Irelia did not believe her senior brother's actions. After a fierce battle, she overwhelmed the seven armies, and collapsed, shouting that she was invincible... (remaining word limit).
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The Zaun arc includes some elements of governance, but at the end of the Zaun arc, it transitions into a pure harem fantasy adventure.