This is an AU
Ryota is in the killing game with the 77 class and Hajime is the Ultimate Vet assistant and he grew up with Gundham

(Ryota POV)

'.....Whywhywhywhywhy' I thought to myself as  Hajime found Sagishi (who was pretending to be Byakuya) dead under the table. "Ha-Hajime." Gundham cried out to the boy who just passed out in his arms. "I- I'll perform a autopsy on him, then I- I'll check on Hajime next. Gundham can you please get him to your dorm since none of us can get into his?" "Ye- yeah sure." Gundham muttered a reply. 'Mh those two seems very close' I thought to myself.

(In the trial)

"So the killer just stabbed him with a knife?" Kazuichi said "No that's wrong." Hajime yelled out. "He was stabbed with a iron skewer about 10 times." The brunette hair male argues. "Do you have the all seeing eye fiend?" Gundham said to the male "No Ibuki thinks Hajime- Chan really smart." Ibuki said. "I- umm thanks?" Hajime said covering his blushing face with his baby blue scarf.
(Timeskip to after the trial because Aruthor- Chan is lazy.)

(Still his POV)

I was laying down on my bed, staring at the ceiling with a blank expression, 'Even if Teruteru deserves it, it is just too cruel. To be cooked alive in a volcano.' I thought to no one in particular. I walked out of the elevator towards my dorm noticing that Hajime and Gundham were walking with each other to the dorm 'Hm I always wondered why those two are very close, maybe because their Ultimates are pretty close or something...' I thought as I walked into my dorm and flopped onto my bed and immediately fell asleep from exhaustion.

(Timeskip to the fourth trial)

(Still his POV)

I stared at Hajime with pity.. poor guy is about to lose his partner.. "Wha- what no Gundham ple- please tell me that it isn't you. Please don't leave me." Hajime cried out to the male who was revealed to be the blackened. "... I apologize Hajime that I went against the promise." Gundham said looking down towards the ground.

Everyone was confused on what Gundham was talking about... "What promise?" Chiaki ask him, "The promise when they were kids of course." Monokuma cheered. "When the were kids?" Kazuichi questioned "He means that they grew up together dumbass." Fuyuhiko said quite proudly. "Ahh alright then." Kazuichi said understanding. "Yep yep, when they were ten they made a promise to never leave each other." Monokuma said while laughing.

I guess that's why they were always do extremely close... even as remnants... 'Poor Hajime. I'm sure that Fuyuhiko will be there for him because he went through the same thing in the second trial.' I thought. "I prepared a special punishment for Gundham Tanaka the Ultimate Animal Breeder." Monokuma laughed "No please." Hajime cried onto Gundham to hold onto him. "Hajime.." I said to him trying to convince him to let go of Gundham.

Hajime reluctantly let go of him Gundham kissed his forehead and Hajime has started to sob now. "It shall protect you now." Gundham said to him giving him a sad smile. "I love you my prince." "I love you too Gundham." They both said to each other but it was interrupted by the chain going around Gundham's neck.

He let out a chock yelp while Hajime tried to reach out for him. Hajime just sobbed onto my chest throughout the execution and I rubbed his back after the execution and he wanted to sleep with me the next few nights.

(Hajime POV)

I didn't think about anything I'm particularly...  'I just couldn't believe it that Gundham was the blackened, I will live for him.' I thought to myself while Ryota trying to comfort me I cling onto him more. He's not that confident in speaking to people so besides Byakuya and are the ones who spoke to him.

(Timeskip to the final trial)

(Still his POV)

I couldn't believe that Sagishi(What Ryota calls him) is the mastermind... even if it hurts Ryota I still have to reveal him as the mastermind... "I know who's the mastermind, the only person who could be the mastermind must be him." I said while pointed to the stand in between the two dead girls.

Ryota like expected got defensive over him... "Wh- what Haj- Hajime please recheck the evidence" Ryota pleaded to me "I'm sorry Ryota he's the mastermind." I said to him giving him a sympathy look "Upupup ding dong you are correct Hajime Hinata." Monokuma laughed.

A foggy mist appears and a shocking sight waited to see us Sagishi was there with... GUNDHAM?!??! "Gah-" Gundham chock out with the knife against his throat, "Gundham." I cried out "Look Ryota and Hajime I spread him." Sagishi said, "Wh- what wh- why Sag- Sagishi. Why did you do this to us..?" Ryota looked at him with fear, poor guy...

Sagishi had an apathetic look at Ryota, "I'm the mastermind Ryota. I'm sorry for not telling you, I'm honestly surprised that you are still alive and didn't die from exhaustion, starvation or dehydration." He said with a smirk, Gundham glared at Sagishi.

Gundham had enough of Sagishi talking, "Y- you're sick you fiend" Gundham said to him with the knife get closer, "Shut up." Sagishi said, "Wha- What the fuuuckk?!?!" Kazuichi yelled out with fear.

(Gundham POV)

This damm fiend put the knife away from my throat and pointed it out towards everyone in the room except for the small mortal male named Ryota. He pushed me towards the ground and leaving little time for anyone to catch me.

My prince Hajime ran up towards me after I hit the ground and went sobbing onto my chest. "Ummm... there there?" I muttered out not used to him crying that much and hard, then I heard the mortal Ryota yell in fear, "Stay away from me you psychopath." "Ah c'mon don't be like that or you will end up as everyone else besides Gundham and Hajime since they have to witness to it." Sagishi 'cooed' out.

I was curious on what the firm was talking about, "Witness what?" I question him. "Us getting married of course." he said while grabbing Ryota's hands. Then everything went black as Hajime laid his head onto my chest passing out and I hold him closer towards my chest as I also soon black out.

1078 words
There would be a part two