In one world, Sawada Nana would have been too sick to take her son to the park that day. In one world, she wouldn't have run into her long-time friend, Sasagawa Masaki, and their children wouldn't have met. In one world, by the time Sawada Tsunayoshi and Sasagawa Kyoko met, Kyoko would have long grown out of her childish ambition.

That is, her childish ambition to make the entire world a happy place for all living beings.

But this isn't that world.

In this world, Sawada Nana was over her cold one day earlier so she took her five-year-old son out to play. This small coincidence was the kindle for both a beautiful friendship and a partnership for the shared ambition that would one day change the world.

One should never take the underappreciated butterfly effect lightly after all.

5 years old Tsu-kun dragged his new friend to the safety of his room upstairs. The fact that they had only met that day wouldn't make him leave her alone with the two enthusiastic mothers in the kitchen. He wouldn't have wished that on anyone. Not even the meanie Osamu who wouldn't let him play.

"Thanks, Tsuna-kun! You really saved me!" She exclaimed as he closed the door behind him.

Tsuna nodded giddily, happy to have found a kindred spirit. His new friend, Kyoko-chan, was an incredible find, she looked like him, she acted like him, they even had the same problems!

"When Kaa-chan brings out the dresses you have to run." The brunet explained wisely to his friend. How he hated being cute! If he was manly like his father apparently was, Kaa-chan wouldn't play dress-up with him!

"I know! When mama starts making my hair, it will always hurt for days!" The little girl complained. The brunet blinked confused. Her mother also played dress up?

Maybe it didn't have anything to do with manliness? Since Kyoko-chan was a girl, obviously her mother didn't expect her to be a man... Maybe this happened to everyone... Oh no, how would he escape the torture then?!

Tsuna held back the panic and tried to distract himself with something else. Then he suddenly noticed some toys.

"Hey, do you want to play something?" And thus, the attention span of the five years old ended.

"Sure!" Kyoko agreed, easily keeping up with the changing subjects. They absently spent time with the blocks and dolls until a bout of loud but muffled giggles returned them to their previous discussion.

"They're not... coming here are they?..." The little girl asked somewhat afraid. Tsuna inclined his head slightly before seemingly deciding on something.

"It... It would be good if they came..." He answered.

"Huh?" She replied, everything from her tone to her eyes screamed 'betrayed'.

"Kaa-chan was very sad this week. She always becomes happier when we play. She says that she likes making Tsu-kun cute." Tsuna explained.

They fell into a short silence as the amber haired girl had a thoughtful expression on her face. Then all of a sudden her features brightened up as if she had understood something.

"So that's why! Onii-chan is always happy when he says I did a cute thing! Cuteness makes people happy!" The girl gushed out excitedly.

Tsuna also smiled an excited grin, that made so much sense! He remembered how everyone would smile at what he had thought was a joke he didn't hear and when the brunet asked they would always answer that he was cute. He had never guessed it before!

"That's true! It happened to Tsu-kun too! Cute makes everyone smile!" The boy gushed right back, Kyoko nodding enthusiastically all the way.

"We can make everyone happy this way!" Kyoko declared seriously, "It's my dream. I'm going to make the all world happy!"

"Really? That's so much better than becoming a robot! I'll help!" Tsuna decided.

They delved into another bout of silence as they went over their making-people-happy-with-cuteness memories. That, though, created another problem.

"How do we be cute, Tsuna-kun? Do we just stand there?" The girl asked inquisitively.

"Umm..." The brunet tilted his head, "Tsu-kun doesn't know..." He answered, momentarily forgetting his self-address in thought.

"We can research though! Like the ones in TV! We'll try everything and see which ones make people smile!" He quickly added on with a smile, the TV had said 'Not knowing is okay, not learning is bad' (in his words) so they just had to not give up!

"Okay! Then we'll tell each other and learn how to be cute! I can even ask mama!" His friend proposed.

After that, for about an hour, they talked on and on about the key to world-wide happiness (cuteness) and even managed to create a schedule until they were forced to separate by their mothers.

By the way, this only helped to steel Nana's resolve to let her little Tsu-kun and the lovely daughter of Masaki-chan meet more often. They were so adorable together too!

And thus, this day marked the fated beginning of Tsuna's sibling-hood with Kyoko (and the steady rise of 'Moe Seduction' in the Ranking Book to first place, far above 'Mafia Seduction' and with 'Reborn Seduction' right under it).

Far away in Italy, a baby in a suit sneezed even as he felt a wave of trepidation go up his small spine. Why did he feel like seducing random women all of a sudden?

In response to his illogical wishes, he shot at his useless student Dino double time that day.

'Day one, the perfect smile ' Tsuna thought proudly, he had been learning to count and he was certain he could master cuteness before he counted to his limit, which was, by the way, currently 15.

1. Attempt

Tsuna looked at his mother. Then he looked. And he looked some more.

His mother stopped mixing the soup and looked back at him.

"Is there somethー"

Tsuna smiled at her warmly.

"ーing you need..."

She faltered but didn't smile or blush.

Not this smile then.

2. Attempt

Tsuna was playing in his room when his mother entered.

He turned his head slightly with the toys still in hand and he smiled a shy smile.

Complete with slightly fluttering eyelashes, tilted head and little blush, it was exactly like he learned from his mother's soap-opera.

His mother stilled, and gasped. Then she smiled sweetly andー

"OH MY GOD! Tsu-kun is sooo adorable!" Hugged the life out of him.

Tsu-kun received that day, a grim reminder. The sombre lesson that shy smiles, especially around energetic young women, were a powerful double-edged weapon only to be used at extreme discretion.

Well, it could still be useful...

3. Attempt

He was watching a cartoon when an unexpected twist to it happened.

So he smiled when the villain unexpectedly seemed to be winning. Only because he was feeling particularly content that day. Obviously.

He wasn't at all excited when the heroes got imprisoned. He also wasn't happy that the situation was seemingly insolvable.

It wasn't his fault that the bad guy always lost and that it was pleasant surprise to have him win. (Although, he lost the very next episode. Damn you, random anti-hero!)

He also couldn't help that his smile was more of a grin and that it looked just a smudge too evil.

Still, the attempt was scrapped when his mother left the room in a way that perfectly embodied the term 'creeped out'.

He would have to learn how to enjoy himself without scaring people away.

4. Attempt

His mother was putting the dishes on the table when he noticed that it was curry.

He was happy enough to feel the need of thanking her. That, and he really wanted to test a recent thought of his.

"Kaa-chan you made curry for me?" He asked.

His mother turned towards him as she put the pot down.

"Kaa-chan," he paused for dramatic effect,

And he smiled warmly (see. Attempt 1) "Thank You"

He also put every ounce of feeling he could into his voice. Everyone knew that love made it warmer.

It went completely different this time, even if the smile was the same.

His mother blushed and gaped at him before giving a huge grin.

Huh, so the appropriate words made cuteness more powerful... He would look into that.

5. Attempt

Actually, this wasn't even an attempt. At first.

He was out with his mother when he was told to stay put and the woman rushed inside a shop.

Fifteen minutes later, his mother was giving him the stuffed lion she bought.

Apparently, since he was 'such a polite gratuitous young man' he deserved a present.

And such a lovely present it was. The fluffy orange lion was absolutely beautiful. He would make lions his favourite animal in its honour.

Anyway, he was inspecting his present, then he realized that this was the best opportunity for an attempt.

So he used the last one he had on his list, he smiled dazzlingly.

His mother stilled.

Then blushed.

Finally, she smiled back to him.

She was skipping the whole day after that.

Well, he thought, this must be success. Now to perfect the perfect smile!

Tsuna annoyed his mother to take him to meet his partner in cuteness for a whole week. After all, they were already behind schedule and needed to talk about their findings on the perfect smile.

After another day of pestering, Nana finally gave in and cancelled her book club to take her son to the Sasagawas. (It was then that she realized how little free time she had. How often had she spent time with her Tsu-kun? Not much, she guessed)

That day was a glorious day for both kids. They had both decided on a smile; Tsuna, the dazzling smile from his smiles and Kyoko, serene smile from hers. (Which also included grin, mischievous smile, smile-with-wink and wild, free smile)

They talked about their other findings, too. Kyoko taught him how to position his head for best effect and Tsuna told her about the actions to multiply cuteness. He also explained her the 'Scrapped Attempt'.

They decided to never use evil smiles and to cover those up with their happier counterparts.

Just as she had said she would, Kyoko had asked her mother about other cute stuff and Mrs. Sasagawa took it upon herself to teach them about cute clothing. Yes, this involved skirts.

Too fast the time passed and it was dinner. Kyoko and Tsuna were taken to the kitchen by her mother. As they climbed on the chairs, the boy tried once again to adjust his very, very long light orange blouse. Although it was comfortably soft, he was too used to t-shirts while this one's sleeves covered even half of his hands and he still didn't understand why this was considered cute.

After that, it was time to leave. The day had been very fruitful, they discussed, rescheduled, combined research and even decided on their signature smile blends (As strange as that sounds): warm and serene for Kyoko, free and dazzling for Tsuna.

That night, he could go to sleep with the promise of waking up to further his, no their, goal of world-wide happiness tomorrow.

Half a month after their 'perfect smile meeting', they had already learned quite a lot about cuteness. They had worked on clothes, gestures, ways of using it on people and even magnifying it with animals and places.

Of course, they were still far away from mastery; Kyoko was having problems with fashion and Tsuna just couldn't get along with that one Chihuahua. But they were progressing.

As things stood, Tsuna's current problem was not cuteness, it was his best-friend's new friend. Now, don't get him wrong, he was not jealous of this new friend. Oh no, he was jealous of Kyoko-chan.

The new friend, Hana-chan, perfectly complimented their fragile innocent adorableness (or at least the image of it that they created) with her strong will and deadly tongue. But of course, she was Kyoko's, even the thought of taking her away made him sick to his stomach. Sharing friends, for some reason, just didn't sit right between them.

So, he decided to do the next best thing he could do. He would find his own Hana-chan...

...somewhere. Hopefully.