"Finally, my journey has reached its end." Tsukasa Kadoya said as his body began fade from existence. Reaching his hand to to grab his Neo-decadriver, Tsukasa pressed a button hidden on the device activating the new Neo-decadriver, "I can only hope that my successor will be a much better man than I was." He said before laying his head down and allowing himself to fade from existence. Once his body faded from reality, the Neo-decadriver began its search for the new successor of Decade.

Universe after universe, multiverse after multiverse, the device went on and on searching for the perfect inheritor. Until finally, it found him residing in the shonen jump multiverse. More importantly in a sub timeline of the Boku no hero academia universe. Activating its protocols, the device zoomed into the universe eager to greet its new wielder.
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Meanwhile in said universe, a lone boy walked down to a junk filled beach, his head swarming with depressing thoughts as he contemplates what he should do next in life. This young man was Izuku Midoriya and the reason he was upset was because a few hours ago he was told by the number 1 hero All Might that he should give up on his dreams.

"Even All Might thinks I don't have what it takes to be a hero." He mumbled out as tears started to form in his eyes. "Maybe I should just give up." He said before a strange portal began to form infront of him.

"Wha----" was all Midoriya managed to get out before he was thrown to the ground by a strange device that flew out of the portal.

"Owww. What the heck was that." He groaned out before noticing an unfamiliar item wrapped around his waste. "Gah! What is this thing! Why won't it come off!" He yelled out as he tried to pry the strange device off.

"Hey stop that!" A voice yelled out from.... the belt?

Startled the teen immediately let go of it, "Calm down kid before someone gets hurt. Okay?" It asked trying to calm the stressed teen.

After a couple of minutes Midoriya finally managed to calm down, "So what are you any way?" He asked while poking the strange belt.

"I'm the Ohma-decadriver and you, my good friend, are my new owner!" The newly revealed Ohma-Decadriver revealed with pride.

"Ohma-Decadriver? What's that mean?" Midoriya asked the driver. "It means that you can become a Kamen Rider." The driver explained.

"A Kamen Rider?" Izuku repeated slowly.

"Oh right, I forgot, you don't have them here." The belt said. "So basically their what you would call a quirkless hero." It revealed, shocking Izuku but before he could say anything the belt continued, "Which is something you've been dreaming of your entire life, am I right?" It asked to which the young man nodded his head rapidly.

"Good cause with me by your side, I can help you make that dream a reality." The driver announced as Izuku fell to his knees as he wept tears of joy completely speechless at what he just heard.
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20 minutes later, Izuku arrived at his home where he was completely overhead by his mother's tearful relief that he was alright. After prying her off himself, he quickly ran to his room and closed the door.

Once the door was locked, the Ohma-Decadriver reappeared around his waste to their conversation from earlier. "So you need to wait around 8 hours before you can actually use me because I'm still bonding myself to your D.N.A and during this time your going to go through some changes because of this, so don't freak out or anything. My recommendation is that you go have some food than go to bed as that'll help speed up the process." The driver explained as it detached from Izuku allowing him to place it on the stand near his bed before leaving the room to go grab himself dinner.

As soon as he left, the Ohma-Decadriver immediately began scanning the room. The reason for this is to find a Kamen Rider form that Izuku can adapt to and better familiarise himself with due to the the fact that when the drive was created, Tsukasa Kadoya realised that immediately giving someone the full power Zi-o or Decade could prove more harmful than useful so to avoid completely corrupting the next user he decide to build the Drive so that it would analyse the next user and chose a form to help them acclimatise to their newfound power.

After Izuku returned to his room and went to bed, the drive resumed it's earlier scans of the room before discovering the teens Quirk analysis books. Using the books as a cross-reference, the drive was able to determine both the appropriate Kamen Rider and A.I that should help him grow both as man and as a Kamen rider. Once the information was properly compartmentalized the device began to take on a silent transformer as to not disturb the sleeping youth.
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When Izuku woke up, the first thing he noticed was the completely different device that sat right where the Ohma-Decadriver used to be.

"Good morning!" The new built yelled out startling the still sleepy teen. "W-w-what the heck?! What happend to the Ohma-Decadriver?! He stuttered out before remembering that his mom was still sleeping and lowered his voice.

"Nothing happened, I simply changed forms to better suit you that's all." The driver revealed surprising Midoriya as he didn't know that it could do that. "Wait, what do you mean to better suit me?" He asked as his hands adopted a thinking pose.

"My creator knew that if someone starts off all powerful than they'll inevitably fall into corruption so to counter that he made sure that his successor (that's you by the way) didn't immediately start of with all his old powers and so I had to get a better idea of the person you were to give you an appropriate Rider form to help you grow before you ultimately use Decades or Zi-o's full powers. To this end, after some thorough analysis, I have come to the conclusion that you would benefit greatly from the Build Drive and as such have activated the A.I replica of Sento Kiryu (that's me) to act as both your guide, mentor, adviser and teacher all rolled into one. That also includes emotional therapy and combat training." The drive explained to a stunned Izuku but before he could speak the device continued, "And once I had reformatted, I had drawn up both a training plan, a learning plan and finally a therapy plan to help improve your self image!" The device announced in a prideful tone.

"W-w-what?" Was all Izuku managed to stutter out to stunned and tired to even think properly. All he could do was wonder what the heck he just got himself into but if it means he can become a hero than he'll sure as heck give it a try.
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1185 words whew, it took a while but after I managing to binge watch both Kamen Rider Decade and Build, I'm confident enough to publish the very first chapter of 'A Heroes Decade (Volume 1)'. I've still got a long way to go before I've fully watched all the Kamen Rider shows but maybe just maybe if I'm feeling up to it, I might introduce Ultraman and the Super Sentai into this story but that's for future me to decide and right now I'd rather get this chapter other with. So please tell me how you thought of this chapter and if there's any spelling mistakes please tell me so I can correct them.