I don't own The Rising of the Shield Hero or Kamen Rider and they belong to their respected owners.

After Fitoria explained the Ahoge on Filo's head and why Naofumi needed to assist the other heroes for the Wave.

"Now, I shall lead you out of the mist," Fitoria says with her carriage behind her. "Fitoria you off near the other Heroes."

"On the dot…" Naofumi sighs.

Before he could say anything else, a zipper sound was heard as they all turned to see a giant zipper zip itself open with red Inves walking out of it and Helheim's Fruits started to grow out.

"What are those monsters?" Fitoria asked before taking a whiff of the Helheim's Fruits. "And what are those rotten fruits?"

"Inves, let me handle this." Naofumi then brought out and opened his Lockseed.

"Henshin."

MELON!

A giant zipper portal opened above Naofumi's head with a giant green sphere before Naofumi tossed the Lockseed in the air before catching it. He quickly caught it before placing it in and locking it.

LOCK ON!

Soon the horn-like sound was starting to play. Naofumi soon put his hand on the knife-shaped lever and pushed it down.

SOIYA! MELON ARMS! TENKA GOMEN!

The metal melon dropped upon Naofumi's head. A white bodysuit formed first and even made his Legendary Shield disappear from his left arm. A helmet formed within the confines of the metal melon. The gauntlets and greaves gleamed gold with black lines rising up his arms and legs. The melon splashed with green energy before opening, the front section coming together in green plating with gold accents. The sides folded together to form shoulder plating but remained slightly separated to give the image of spikes. The back pieces landed on the back, finishing the armor.

His helmet was revealed to have large eyepieces with a silver mouth-plate and a gold crescent moon on the forehead. The helmet attachment was designed like the skin of melon with gold sidings like a samurai helmet and a melon stem coming from the top. The attachment had caused the eyes to turn green, giving them a look, not unlike a slice of melon. A flash of light appeared over his left arm, creating a large shield with a golden center ending in a crescent moon with gold siding and a round disk on the top. The rest was covered in the same textured green as the Melon Arms. This is Kamen Rider Zangetsu.

Zangetsu ran past the girls. with Musou Saber raised and slashed the Elementary Inves.

Zangetsu blocked when Inves tried to slash him before impaling the gut of the monster with his Musou Saber. He then turned around and slashed another one with his sword before pulling out pulled the trigger on nearby Inves. There were still more red Inves coming out.

Zangetsu pressed down his Cutting Blade once, activating his finisher.

MELON SQUASH!

After Zangetsu activates his Sengoku Driver's Squash function, he charges the Musou Saber with melon-shaped energy before slashing the enemy.

"No, you don't!" Zangetsu shouted as he tried to slash the red Inves from eating a Helheim Fruit but it was already too late.

The Elementary Inves was starting to change, it grew taller to Zangetsu's height, it became a Lion Inves but it had red wings and looked angrier.

As Zangetsu tried to slash the Lion Inves but got slash back by its claws sending him stumbling back.

"Master!"

"Naofumi-sama!"

His companions ran to his side to check if he's okay.

"Are you okay, Naofumi-sama?" Raphtalia asked worriedly.

"I'm fine but damn that hurt," Naofumi muttered.

"Here." Fitoria getting their attention.

Everyone looked to see her holding a Lockseed which had the image of a watermelon with the word LS. 10 on it.

Naofumi took the Lockseed and looked over it. "How do you have a Lockseed?" Naofumi asked.

"As the years go by I forget many things but I will always remember this. The hero who raised me was offered the same belt as yours but denied to use it." Fitoria answered.

"Someone was offered to be a Kamen Rider?" Naofumi looked more confused.

"Is that what you call yourself?" Fitoria asked.

"Master is called Zangetsu!" Filo exclaimed proudly.

"That's the name that was offered to the last Legendary Hero," Fitoria says.

"Naofumi-sama this sounds really convenient with your armors and these Lockseeds," Raphtalia says.

Naofumi frowns under his helmet. "Too convenient… but with how that stupid Lion Inves being too strong, I guess it won't hurt to have an upgrade." Naofumi opens the Lockseed.

WATERMELON!

A Crack zip opens above Zangetsu and brings down a green metal watermelon. The main difference between this watermelon than the Suika Arms is the size.

Zangetsu then replaces the Melon Lockseed with the Watermelon Lockseed into his Driver and locks it in.

LOCK ON!

Suddenly his faceplate made a slight change in colors before Zangetsu pushed down his Cutting Blade.

SOIYA!

The Watermelon Arms soon dropped onto his head immediately as everyone noticed a sudden change in color happening to Zangetsu's bodysuit. The gauntlets and greaves turned from gold to red as the Watermelon Arms began to disassemble in the same way as the Melon Arms did. Instead of his gold horns, Zangetsu has red horns along with a red visor.

WATERMELON ARMS! MIDARE-DAMA, BA-BA-BA-BANG!

Emerging in his hand is a watermelon theme shield resembling the Melon Defender, but the bottom part has a minigun attached in place of the sharp point. This is Kamen Rider Zangetsu Watermelon Arms.

"Are these gun barrels on my shield?" Naofumi asked as he looked at his new shield.

"What is a gun?" Melty asked, looking at Zangetsu's new shield.

"I guess I'll show you," Naofumi says.

They saw red Inves walking towards them. Zangetsu lifted Watermelon Gatling so the mini-gun of the shield aimed at the Inves.

"You might want to step back," Naofumi informed them, he never fired a gun before, much less a mini-gun, and was pretty sure it's going to have a hard recoil.

The girls all stepped back as instructed as Zangetsu pressed the trigger that was inside the shield and started unloading bullets at the red Inves destroying them from the powerful hits. The girls covered their ears and flinched from the loud noise coming out of Zangetsu's shield.

And as Zangetsu predicted he gained recoil from using the Gatling gun now made him weak but that wasn't going to stop him from destroying the Lion Inves.

"That was loud!" Filo whined.

"What kind of shield is that!" Melty says, her ears still ringing.

"Sorry, but I'll end this now!" Naofumi says, throwing away his Watermelon Gatling to the floor.

Zangetsu then pressed down his Cutting Blade three times, activating his finisher for his Watermelon Arms.

WATERMELON SPARKLING!

"Haaa!" Zangetsu jumps into the air, engulfed by watermelon-like energy-focused that was his left foot as he strikes the Lion In with a powerful kick destroying it into a fiery explosion.

Zangetsu landed on his feet and removed his Lockseed and Senkou Driver returning back to his normal attire.

"Well, glad that's over," Naofumi says as he inspected the Watermelon Lockseed. "This gave me a huge recoil and used much of my body's strength to use the Gatling gun."

"By that tone, it means you won't be using it that often," Raphtaila says.

"Only for emergency and surprise attacks." Naofumi nodded.

"Shield Hero may I speak to you?" Fitoria asked.

"Sure, what is it?"

"The last Legendary Heroes weren't killed by the wave. They beat swiftly and no sacrifice." Fitoria says.

"Then how did they die?" Melty asked.

"By an armored warrior similar to yours." Fitoria pointed at Naofumi.

"They were killed by Kamen Rider?" Naofumi raised a brow.

"As I said before, the last hero who raised me rejected the offer to be Zangetsu," Fitoria says. "The man who gave him the offer came back with three armored warriors."

"Do remember what they look like?" Naofumi asked.

Fitoria nodded, "Yes, one was in white armor that could fly, a spear holder that had a green A on his chest and a red jewel on the center of his helmet, and the last one was a woman in silver and grey armor with a green weapon on her waist. Her weapon shot projectiles were similar to your new shield."

"What happened after they killed the Legendary Heroes?" Raphtalia asked.

"The mystery man summoned a blurry wall and took them away and haven't been seen since," Fitoria said.

Naofumi rubbed his chin, "So there's Dark Riders who could probably come back and kill us." Naofumi groans. "Things just got more difficult."

AN: How about this, I had this in my folder for a while and couldn't figure out where the setting should be till now. There's only one Zagetsu/Shield Hero crossover which was created by Artzilla406 and their story is a bit, not my taste so I created this and used the Watermelon Arms, his upgrade form.

I also planned on giving the other Legendary Heroes Drivers but since they were jerks to Naofumi they don't get epic ones. Motoyasu Kitamura as Leangle, Itsuki Kawasumi, Ren Amaki as Kaxia, and I'm still struggling with Itsuki Kawasumi because I'm not making him Chalice or a New Generation Riders, we already have Zangetsu. So I just plan on giving him the Attache Arrow with perhaps 10 Progrise Keys maybe 6, but I don't know if he should be Horobi, Jin, Ikazuchi, or ZeroZero-One. Chose for me or PM, It's a struggle in my mind.