Ienobu Sawada is Tsuna's younger twin brother.
Tsuna loves his brother.
When they were too small to understand why at the time, their mother left them at a daycare. Tsuna stood uncomfortably in the middle of the room. All the other children were playing and running around him. Ienobu noticed his brother's displeasure and decided to drag him over to the oversized building blocks. However, Ienobu had to leave to go to the bathroom.
A few slightly larger kids walked up to the unsuspecting Tsuna. He yelped outright when one of them destroyed his tower. Tsuna tripped over the debris, and the bullies surrounded him. One began to shout at the fallen boy, but all Tsuna could remember was being frozen in place. His ankle, the right one, it was hurting so much more than all those other times he tripped over his own two feet. And was it really his fault that he did not know the building blocks belonged to these bullies?
The prepubescent tormentor grabbed Tsuna's shirt. The shy boy could do nothing else but close his eyes, shaking profusely and turning his head away from the bully's wet breath.
One second later, Tsuna felt the hands suspending him over the floor release. He fell on his bottom again, the outburst of pain prompting him to open his eyes.
Ienobu was there, standing over Tsuna's attacker. The bully was struggling underneath Ienobu's foot as his companions, visibly surprised with wide eyes, backed up a step or two. The younger twin, his face in an unreadable grimace, turned to his brother and offered his hand.
During subsequent yet rare daycare visits, the Sawada twins experienced few bullying incidents. They were either left alone or partook in brief conversations with the other kids.
Tsuna loves his brother.
One day, the daycare was closed, and all of the twins' usual babysitters were unavailable. The six-year-olds were told by their mother to remain in their backyard for the rest of the day. Tsuna readily followed their mother's orders. She seemed stressed about something for the past month, after all, and he was a good son that wanted to let her relax. Ienobu, on the other hand, walked alongside Tsuna with a frown.
Ienobu also seemed to be bothered by something when kaasan sent them outside. The tension in the Sawada household mostly flew over the oblivious Tsuna, despite the underlying cold spot he felt. Ienobu refused to explain his frown, and Tsuna chose not to dig in further.
Tsuna was halfway done with his sketch of his favorite Megaranger when Ienobu told him that he was going to use the bathroom inside the house. They both knew about the bucket kaasan had left in the corner of the yard, but Tsuna only nodded with half closed eyes. He loved his mother, but the bond with his brother, Tsuna realized, was greater than his love for their kaasan. If Ienobu wanted to find out what kaasan was hiding, then Tsuna would let him.
The yelling reached Tsuna's ears not too long after Ienobu went inside. Tsuna ran just in time to see one of kaasan's friends, the one always dressed in the nice suit, jumping down the staircase saying very bad words. The man was nice since he always gave him and Ienobu fruity candy, but Ienobu at the moment was screeching as well, chasing the man with a broken tree branch. The Sawada twins liked to have pretend sword fights, and the younger Sawada was utilizing his training to the fullest.
Kaasan came downstairs as well, trying to hold back Ienobu. Tsuna started screaming, too, loudly asking what was happening. Kaasan's friend gave him a look, one that Tsuna couldn't discern. It was too quick, and Tsuna could hardly try to get a second glance as the man walked out the front door. Ienobu threw his stick, successfully acing a hit at the man's back.
Still, the loud bellows did not cease. When it was clear the man would not come back, Kaasan slammed the door shut and turned her unusually red face to Ienobu. They screeched at each other, spit flying and the noise hurting Tsuna's ears. The confused child had to cover them up with his hot hands. Kaasan was bellowing something about listening to your mother and being a good son while Ienobu was shouting about loyalty to family and… and otosan.
Another deafening howl joined the clamor. Tsuna demanded to know what was happening. Why was kaasan's friend here? Why did he leave? Why did Ienobu chase him out? Why is kaasan slappin –
Kaasan slapped Ienobu, right on the cheek, the irritant noise resonating even through Tsuna's palms. Ienobu's feet slid on the wood floor, almost in slow motion in Tsuna's eyes. The younger twin went down, his arm smacking the timber. He blinked rapidly as he touched the pink skin hesitantly. His lips quivered, as if he suddenly lost all control over his ability to speak.
After what felt like an eternity, Tsuna could hear Kaasan walk away, the footsteps brisk and echoing in the silence. She might as well have been on the other side of the planet, however, as all Tsuna could comprehend was his brother's fallen form.
Like the good onii-san their classmates always said Tsuna should be, Tsuna wrapped his arms around his brother. Ienobu hugged back, burying his head and gravity-defying hair into Tsuna's shoulder. He mumbled things Tsuna failed to hear clearly, but that was of no matter. Tsuna could find out what exactly happened later. All that mattered now was taking care of his brother.
Tsuna loved his brother.
Over the next four years, Tsuna had to deal with the rising distance between his brother and his mother. During meals together, they never made eye contact or said more than ten words to each other. When the twins came home from school, Tsuna liked to hug kaasan while Ienobu rushed to their room upstairs. Whenever kaasan was called by the school or police for some act of disobedience Ienobu committed; a string of failed grades here or an apprehension for graffiti there; Tsuna had to watch his mother become another person. She became colder, expressionless, void of pride, annoyance, or even disappointment.
Separately, they acted fairly the same when around Tsuna, cordial and like a true family member. He took a very, very small comfort in that, even when a part of him thought he should be doing something more to fix the problem. It wasn't like the occasional bully and Tsuna's own natural clumsiness weren't taking up too much time out of his life, though.
On one of those days where Kaasan was out of the house, Tsuna reeled back at the two strangers sitting in his living room. He had just come home, escaping another intense chase from a hound, when a muscular shirtless boy with white hair greeted him, extremely.
It wasn't long until Tsuna was told that Ienobu, applying bandages to the other boy's nose and fingers, had encountered the two strangers apparently caught up in a street brawl amongst middle schoolers and elementary students. Ienobu, in worse condition with the Tsunayoshi trademark beaten and broken body, invited the newly introduced Ryohei and Kyoko to his house.
Realizing what injuries Ienobu, the damnable violent munchkin, had sustained and left untreated, Tsuna promptly retrieved Ienobu's secret stash of stolen medical supplies (even Tsuna didn't want to know the details. All he cared about was that they were useful at patching up both twins' injuries). Ryohei's younger sister, Kyoko, assisted Tsuna with his treatment of his brother.
"Onii-san is fine now," she said in a cute, sweet voice, "and he should have learned his extreme lesson." Ryohei abruptly halted his shouting for a few moments. "Let me help. Think of it as my thank you to your brother, Tsunayoshi-san."
"Call him Tsuna-kun!" Ienobu commanded, seeing the obvious tinting in his twin's face. The glare failed to falter the smirk.
"Alright," Kyoko chuckled, causing Tsuna to refocus is efforts into wiping alcohol on Ienobu's abrasions, "Tsuna-kun it is, then!"
Sometimes, Tsuna hated Ienobu.
But he still loved his brother.
Eventually, the bullying finally stopped in its frequent and infrequent occurrences. Maybe it had something to do with Ienobu building himself a reputation of being a violent delinquent.
Ienobu liked to wander the neighborhood. He ran into street gangs a lot, he claims, and decides to try and beat them all up to "test his capacity."
After some talks with him and Kyoko, Tsuna decided that he and Ienobu should join the boxing club. Kyoko knew just how dangerous attacking gang members were, and Tsuna believed all Ienobu was doing was finding an outlet to relieve his violent tendencies. And he did have them, no matter how hard he tried to hide them from his onii-san.
At least in the boxing club, Ienobu could probably learn better self control. And Tsuna finally summoned the courage to try to learn self defense and self control as well. Tsuna was naturally clumsy, and he didn't want to risk dropping his brother's unconscious on the way body back home, or to have to do it at all.
But he did, not long after Tsuna quit the boxing club, to Ryhoei's massive disappointment.
Tsuna found Ienobu twitching in the middle of an intersection, face planted against the concrete. Hibari, the Hibari, leader of the Namimori Disciplinary Committee, was standing over him. Sasagawa, somehow hanging upside down from the dense leaves and branches of a nearby tree, was, as always, screaming his head off.
The stare Hibari gave instantly made Tsuna freeze.
When a phone call whisked the animal away, Tsuna immediately went to his brother. Sasagawa freed himself and EXTREMELY chased after Hibari.
At the start of junior high, Tsuna expressed his concern of the band around Ienobu's arm, and of the responsibilities that accompanied it. Of course, Tsuna promptly fell over his feet and into the base of a tree trunk. Ienobu laughed goodheartedly and pulled his twin up, waving off his concerns.
The year passed, and the twins got to meet two of Kyoko's friends: Hana Kurokawa and Takeshi Yamamoto.
The next school year was coming soon.
And throughout it all, Tsuna will always love his brother. That was a promise.