Fifth season of Hua Jianghu: Bu Liang Ren.

In the mysterious future, crystalline organisms called Gems inhabit a world that has been destroyed by six meteors. Each Gem is assigned a role in order to fight against the Lunarians, a species who attacks them in order to shatter their bodies and use them as decorations. Phosphophyllite, also known as Phos, is a young and fragile Gem who dreams of helping their friends in the war effort. Instead, they are told to compile an encyclopedia because of their delicate condition. After begrudgingly embarking on this task, Phos meets Cinnabar, an intelligent gem who has been relegated to patrolling the isolated island at night because of the corrosive poison their body creates. After seeing how unhappy Cinnabar is, Phos decides to find a role that both of the rejected Gems can enjoy. Houseki no Kuni follows Phos' efforts to be useful and protect their fellow Gems.

That jumbled piece of architecture, that cacophony of hissing steam and creaking joints, with smoke billowing from it as it moves on its own... That castle is home to the magnificent wizard Howl, infamous for both his magical prowess and for being a womanizer—or so the rumor goes in Sophie Hatter's small town. Sophie, as the plain daughter of a hatmaker, does not expect much from her future and is content with working hard in the shop. However, Sophie's simple life takes a turn for the exciting when she is ensnared in a disturbing situation, and the mysterious wizard appears to rescue her. Unfortunately, this encounter, brief as it may be, spurs the vain and vengeful Witch of the Waste—in a fit of jealousy caused by a past discord with Howl—to put a curse on the maiden, turning her into an old woman. In an endeavor to return to normal, Sophie must accompany Howl and a myriad of eccentric companions—ranging from a powerful fire demon to a hopping scarecrow—in his living castle, on a dangerous adventure as a raging war tears their kingdom apart.

Two martial artists are brutally killed by a team of assassins, leaving their wards, a young boy and girl, defenseless. A martial arts master dispatches of the assassins, sparing their lives, and decides to take them in. He raises them and teaches them martial arts.