Fumi shifted his weight and braced his hands on the ground.  Resting on all fours he panted and observed the white stain of his passion spread out and turn the Seine pale. He ran his fingers over his still flared glans and shuddered, a thin trail of saliva passing his lips. 

"N-nyaa- You make me so hot when you touch me." Fumi murmered, enamored with the millions beneath his shadow- or more accurately the sensations they brought to his magically-enhanced flesh.

Loping north on his hands and knees, Fumi passed over the ruins of Ile de France and crossed in just a few moments over Amiens and Lille; shaking the smaller cities apart with his passing. 
He found himself facing two large cities within a 'foot' of one another, and sat on his heels between them. 

"Nya- I want you all so badly." He chirped, gently cupping his still hard shaft. "But there was way too much city between us last time. What to do- what to do?" 

Fumi knowingly flicked his hand, again conjuring an object from his unseen panoply. This time it was a small brass ring, engraved with black inset runes. He slipped it wordlessly onto his pinky and regarded it proudly for a moment before clenching his hand shut and sticking the little finger straight out at one of the cities.
At once the landscape echoed with an arcane hum, and for a dozen miles around the city center there seemed to be a slight bronze-colored glow, eminating from every human who Fumi focused his gaze on. 

"Nya- got you!" 

With a sudden jolt all 2 million inhabitants of Brussels lifted off the ground- only spared instant obliteration by the magical protection the field seemed to offer. Any who were inside buildings or underground passed through walls, concrete, and soil with whatever force neccesary to bring them high into the air in a vast field several miles above the ground, framed squarely between Fumi's pale thighs. 
"Good, the protection worked. Would've been awful messy if it hadn't- Fufu~. Unfortunately for you little guys it's gonna get messy one way or another." Fumi giggled at his own joke and swiped his hand gently through the cloud of suspended humanity, gathering them up in his palm.

With his free hand Fumi steadied his cock and lifted it until its still reddened tip pointed straight skyward. Had he stood at his mundane height his smooth uncut penis would have been almost nine inches long. At his continental height however, Fumi 's cock rose 25 miles above his sizeable balls; which themselves could -and currently did- cover a small town beneath their oppressive bulk. With a flourish of his hand Fumi spread the swarm of humanity into a thin cloud and draped it like a tissue over his penis, letting the microscopic specks settle densely atop his glans, on the wrinkles of his foreskin, atop any vein that would accept them, and generously atop his sack. 

The tiny humans atop Fumi's cock enjoyed a more generous amount of space per capita than they ever had in their city. Those who settled onto his glans found themselves in a miles-wide gently sloping field of summer-sidewalk hot pink skin. His arousal seemed to roll off of it like fog off the peak of a mountain.

Those who had landed nearest his urethra couldn't keep their footing as his cock pulsed beneath them, and thousands tumbled down it's inconcievable depth. Those who about his drawn-back foreskin were tucked into it's slick recesses and held in place by uncountable tonnages of loose skin. 

Atop his immense balls three hundred thousand could hardly remain standing for all the jostling and shifting beneath them; mere twitches to Fumi who had begun to react with moans and gasps of pleasure from the magically-heightened sensation their presense brought him. Any who slipped into the crease between them were crushed between unfathomable masses when the shifting orbs pinched together between his shifting heated thighs. 

"Nya~ Fuck!" Fumi spouted. One of his hands framed the base of his cock and his other rose to tweak at a stiffening nipple. If pressing into the cityscape before had been akin to masturbating then such direct contact with so many mana-yielding tiny humans were the passionate throes of love making. 

Those who had fallen down his flaring slit were brought back up in just a few moments by an immense bead of clear pre-cum, which rolled over tens of thousands of humans in it's path as it slowly slid across his glans and dripped onto his fingers far beneath. Fumi brought his hand up to his face and turned the sticky bead over; his keen eyes just barely able to make out the countless motes caught in it like amber. Fumi giggled maliciously and deftly kissed his finger tip, savoring the taste of salt on the tip of his tongue. 

Only a minute had passed and Fumi could already tell the jostling environment of his crotch had claimed most of the mana it's millions of occupants could offer. Between the rolling landscape of his balls and the throbbing shear cliffs of his shaft most had fallen or been crushed between some heated wall of skin or another. 

"Nng- One city isn't enough to make me cum? So pathetic, Nya~." He mocked, dragging a fingertip down his shaft and reducing yet another swathe of humans to unnoticable stains on his cock. "Nya, maybe your neighbors will do better!"

Fumi again flashed his ring, this time at another sizeable metropolis between his feet. Another two million humans were drawn into his cupped palm and this time shaped into a long thin shape, still only half the length of his cock. Without warning Fumi grabbed hold of this formed mass of ensnared tinies and pressed it's lower end against the tip of his cock. Fumi shivered at the sensation of so many humans pressed against the hypersensitive entrance to his urethra. 

"Nng- down you go! Squirm lots for me!" 
Fumi slowly pushed the long mass of humanity into the hot sticky depths of his cock, throwing his head back in pleasure at the overwhelming sensation of so many mana-bearing forms scraping off against his skin or struggling against it as they were shoved miles down it's length. 

Had it not been for the practically solid mass of supplicants filling his urethra he would've came instantly, but their presense kept his pleasure bottled up as he slowly threaded the populace into his shaft until the last of them dissapeared into his flaring glans. Fumi sat practically entranced with pleasure, his hands firmly grasping at the earth astride him and churning small towns and forests into mud between his fingers. Then with one final quivering 'Nya~!' he grabbed hold of his painfully rigid cock and began to stroke it uncontrollably. 

It took both hands to properly wield his girth, and he only spared one momentarily to cup at the base of his shaft, feeling a slight lump as the bottom as the mass of humans finally reached the base of his cock after their 20 mile descent. Fumi fell onto his back, and as he reached the end of his endurance his cockhead pointed towards his chest. Fumi bit his lip and began the last furious throes of his masturbation. 
Then all at once the dam burst and Fumi's efforts to keep those millions of humans

within him aligned into a living sounding rod were abandoned. Fumi put his prior ejaculation to shame. 
With a high quivering cry Fumi's cock spurted long strands of pearly ejaculate across his body. 

His crotch was blanketed with it and became a vertiable sea of cum, filled to the brim with those humans who had been lucky enough to stay atop the rising caldera of semen until the end. Ability or aptitude at swimming mattered little, as his semen was heavy enough that those buried beneath it were lost, and thick enough that those atop it's surface were held helplessly in place. 

His navel filled over and became a trench deeper than the Marianas. His release made it to his chest, and a few populous strands graced the field of his chest or draped heavily across his elegant neck. 

When Fumi's cock finally began to drool atop those few who had survived on the shaft and balls, he slumped fully onto his back and panted in orgasmic bliss. He streamed with sweat, and his butt, arms, and legs were coated in sticky mud where his writhing had churned the coast of Belgium into a shallow inlet of the Channel.  
"So good, unh~. You humans are something else~." He whispered at the metropolis his head had landed beside and atop which his feathery hair had cascaded atop.
He closed his eyes and fell into a gentle sleep.