Can somebody explanin me what is The Manga about. I read it but i didnt Understand it. Als...

Hey! I'll try my best to explain the manga to you, but i apologize in advance if it gets too confusing. I tend to do that...(I'll be telling this from memory, so please do forgive me for a lot of missing details. This summary/explanation is to and from the whole manga.)
To get to the whole point in this manga, Moto has been trying to find this man called Itan. Itan was Moto's really close friend and they even lived together. To others though, Itan was a really cold and violent person who only smiled and cared for Moto. One day though, during an incident, the police were chasing Itan and Moto. (I really don't know why.) Itan saved Moto by pushing him away and telling him to hide. The police took Itan away after that and sent him to jail.
That was how Moto ended up on the streets. While Moto was riding the bus/train/subway, he saw Sezz. Sezz just got out of a wedding and was having a bad day. So, Moto did what everyone would've done if they saw a worn out handsome man. Steal their wallet. Moto stole his wallet and thought that he didn't knew, But Sezz ended up chasing after him. That was how Sezz and Moto's relationship started.
Not long after Sezz and Moto started to live together, Moto met Itan again on the streets when they were going shopping. Itan had the plan to take Moto back so they could start living together as well since he's out of jail. But at this point in the Manga, Moto was already falling for Sezz and only looked at Itan as a close friend. Moto goes to Itan's house and didn't have the guts to reject his offer. So he hid it from Sezz.
The second time Moto went to Itan's house, Itan pushed Moto down and decided he wanted to rape him. A.k.a "making him mine." At the same time that was happening, The police came to Itan's house. Oh, the perfect timing. Well, Moto didn't run up to the door and yell "Help me," but rather he helped out Itan ad chased the police away. (Oh right, Itan murdered a guy by blowing up their car.)
Moto tells Itan that he can no longer trust him and asks him "Why did you d this?" He fell asleep afterwards watching Itan leave the house.
The next morning, Moto wakes up not seeing Itan in sight. He had a gut feeling though and ran back home (to where Sezz is.) When he did get back, the house/apartment/room was all messed up and broken and Sezz was not in there. So, Moto did what everyone would've done in this situation and tried to find Itan and Sezz.
The same time Moto is trying to find them, They'll show you some panels of Itan and Sezz. It seems that Itan was heavily mad at Sezz for "taking away Moto," and planned on killing him. Things got down and Moto arrives. I'm not sure what he said 'cause well, i can't read the Spanish raws. To put it in conclusion though, he leaves Itan for Sezz.
After a while, Moto sees Itan again on the streets. How convenient. He agrees to talk to him and they go to somewhere private but open. Itan says that he is sorry for what he have done to Moto (I am assuming.) Moto kissed Itan but tells him that they can never go back to the way he was before.

That was practically where it left out on. I forgot to mention that Moto had a twin(?) brother of his. There was also a really powerful man that got Itan out of jail. It seems like he has a liking to Moto also. I know that was very long but i don't think its too confusing. Rather than an explanation, i gave you a summary LOL. To mention once again, this is from pure memory so i know i left out a lot of details.
I hope that helped.

Oh, and what do you mean by the little boy? Could you provide me a chapter/page for that scene/panel?

I mean The extra, The Last chapter. When they are at The amusementpark. There are two Guys and The Little Boy. Who are they. And thank you very much for The summary.

Hi! Okay, so judging from page 8 of the chapter, the little boy is Moto.
http://www.mangago.me/read-manga/the_summit/tr/46982/page/8/

The guy in the suit is the father and the guy with the school uniform in the son. I honestly don't know who the father and son are, just for the fact that the little boy is Moto. I would assume that the guy in the uniform is Itan, but i'll just be jumping to conclusions too quickly. At this point, i don't think anyone knows.

Okay. Conclusion #2. The guy in the uniform (the son), could most possibly be that one guy with all the power and money. (The man that released Itan from jail.) I don't recall his name in my mind but he appeared in a few chapters from the main chapters. But other than my assumptions, it's really just a dead end for me. Sorry LOL. This is more likely than my first assumption.