Okay.
It's 199x.
Demons start coming out of nowhere, thanks to Steven Hawking (the true enemy). His teleporting powers of destruction opened up a connection to Makai and demons want to crash the party in Tokyo.
A general tries a coup-d'etat using the demons. America intervenes. There's also this girl called Yuriko who wants to be with you but can't have you because you're destined to be with this other girl who is an underground resistance leader.
Thor, who is also the American Ambassador, launches ICBMs aimed at Tokyo. After they hit, you wake up in Makai which is like Disneyland with a two drink minimum.
You end up 30 years in the future. It is not as it seems. Eventually you run into your dog who, before the world changed, you fused with a demon to turn into Kerberos. He rocks out with his rooster out. You also get the underground resistance leader girl back who wants to be your Eve. Yuriko is also around and eventually reveals herself to be Lilith and that's not cool. Well, it kind of is, but that's not the point. You have to kill her because she's a meanie.
Steven is here in the future, as well a dude called Louis Cypher. Steven is, of course, plotting. Louis is doing stuff.
Eventually Tokyo gets flooded because someone left the plug in the drain so you collect some items and then go into the final dungeon and either fight chaos, law or both. Neutral is the canon. You tell both sides to **** off and go build your own future.
 
50 years later, the next game begins. You begin as a gladiator called Hawk. You're in Tokyo Millennium. Steven Hawking is still around. He's now entered himself into the matrix... of the virtual battler so he can give you programs. He's still plotting.
After beating a dude called Red Bear in the Colosseum, you end up being able to go to Center, which is in the centre of Tokyo Millennium. This girl called Hiroko joins you before you go there though. Also, you meet a guy called Zain who tells you that your actually called Aleph. You also are a citizen of Center as well.
Screen fades to black and then you're in Center, speaking to some bishop-type man. Hiroko leaves. There is something important revealed to you. You're Aleph and you're Jesus. Or, as I like to call him, Jésus. You're joined by a girl called Beth.
You're sent to go defeat King Frost.
Meanwhile, Steven is still hanging around in the virtual battler.
Later on, Red Bear reveals himself to be Daleth. He thinks he's the messiah and calls Aleph the impersonator of the king. Or the messiah. You fight him again. He kills Beth. You defeat him. Beth stops Aleph from killing him.
Further on, Aleph's informed to go stop Mekata who's a person. When Aleph meet Mekata, he tells Aleph that Hiroko is now imprisoned for being a heretic and Aleph goes to save her. You fight Daleth, a demon called Naja  joins the party and then you fight Zain on the way. Hiroko is trying to ignore Aleph so Naja fuses itself with her and Hiroko gets bored of ignoring him. Then she joins again.
On the way back, Aleph meets Zain again who points out that the area of Tokyo Millennium called Valhalla was swallowed by Abaddon. Kerberos also joins you because he wanted to rock out with his rooster out in the future as well.
Zain starts going completely against Center, Aleph heads into the underworld (which is the ruins of original Tokyo), he fights Daleth one last time, helps Hiruko revive Lord Masakado, meets Louis Cypher who also wanted to hang around in the future, helps Zain save some people and sends Siren to Makai by finding her dead boyfriend. Steven is STILL hanging out  in the virtual battler.
Aleph ends up going into Center to fight with all his might. He kills the angels Raphael, Uriel and Michael (Jackson).
Then you get to wail on Shinryou YHVH. Gabriel appears, informing you that he and the other three angels built Tokyo Millennium, then the other three ruled it. Turns out that Gabriel was following true YHVH and you didn't kill the real deal.
Steven is still in the ******* virtual battler, still handing out programs. He's also nearly done plotting.
Aleph ends up going to Makai and meets Steven in the flesh. He's almost mastered his teleporting powers of destruction and has set up terminals so people (and demons) can go places. Aleph ends up meeting Louis Cypher who reveals himself to be Lucifer and asks if he wants to hang out at his castle (Castle Kether) because he's cool like that. A bit later on, Gabriel takes Aleph to Eden and you talk to Zain there.
So Aleph heads to Lucifer's crib and they hang out. Aleph accidentally spills some Apple Juice. Lucifer ends up trying to kill him but Aleph wins. Then he meets Steven again. Steven warns him that Kuzuryuu is going to wake up and murdilate everything. Daleth asks Aleph to stop Kuzuryuu as well so Aleph does.
Steven then tells Aleph to go to Eden. When Aleph gets there, he hangs with Zain for a bit. Then Zain reveals that he is actually Satan. Aleph trips and falls into the underworld. Steven then tells him that  There was an ark built in center. Inside the ark is Megido Arc, a super-powerful laser. The ark is launched from Tokyo Millenium and Satan will use Megido Arc because YHVH doesn't care about the world anymore. Steven, almost done plotting, teleports Aleph to Eden. He ends up fighting Satan and winning because Satan wasn't angry enough.

Eee... thanks for the sumary but i meant those for nes/FC A.K.A "Digital Devil Story: Megami Tensei" I & II,and their remake "Kyuuyaku Megami Tensei"
http://en.wikipedia.org/wiki/Digital_Devil_Story:_Megami_Tensei
http://en.wikipedia.org/wiki/Digital_Devil_Story:_Megami_Tensei_2
http://hg101.classicgaming.gamespy.com/megaten/megaten.htm
I know that the most basic part of the story is similar to the SMT I&II games and The book(as I said I did read the book) I also played the SMT games too. I would play The nes games but I dont know how to read japanise. Anyway thanks, but could someone give me the sumary of the NES games or Kyuuyaku Megami Tensei?

ALSO: Steven is the embodiment of Neutral, not Chaos.

Megami Tensei I is almost story-less. All the game is one single goddamn freaking huge dungeon, with Maoh Lucifer at his end. There are 5 other Maoh, but 3 are optional bosses. There isn't really anything beyond " Trudge through six areas , Kill Lucifer, Save the World ". It supposedly take place during the book.
 
SPOILER ALERT !
 
Megami Tensei II is a little more interesting. It starts half a century (more or less) after the first, in Tokio (obviously). It's revealed that a nuclear war almost destroyed the world and now the human race struggle for survival in a world overrun by demons. The character is a young man, playing a videogame/training program in a nuclear shelter, with a friend watching him. This videogame, Devil Buster, is actually the very first area of MT I, with the same objective (kill Minotauros ). After doing that, the Hero and his Friend are contacted by Maoh Pazuzu, portraing himself as a ally of humanity and asking for their help to defeat Maoh Baal, the ruler of Tokio, calling the Hero " Messiah ". The game then ends and the Hero and the Friend, after beating a boss in the shelter, set out to the other areas of Tokio.  
 
After a while, Pazuzu asks them to go kill a Witch in Tokio Tower. This witch is actually the Heroine, who accuses them to be simply pawns of Pazuzu in a power struggle between Maoh. You can then decide to believe your power-hungry friend, who likes very much his new role as a Messiah, or her.  
I don't know if there are any real changes in the story based on this choice. I selected her but beside having to fight the Friend a couple of times and having the heroine abducted by Astaroth i never encountered anything that seemed character specific during the game.
 
During the journey the characters stumble upon the supposedly defeated Lucifer sealed in Ice under Ginza, learn of the existence of 7 pillars needed to reach Masakado, and defeat all the other Maoh. After defeating Baal the characters have to travel to the Makai with the help of Masakado and reach a resurrected Lucifer. By having the characters sparing Baal, who upon his defeat transforms into a frog, you will then be able to enjoy one of the best secrets ever in a Megami Tensei. After reaching the penultimate Maoh, Beelzebub, he will recognize the frog as his " other self ", that was separated form he by the Only God (dear old YHVH ), and then fuse with it to become a Majin, Baal. He will then ask to join you. He is a very good ally, with powerful healing magic, but it's real value becomes apparent after reaching Lucifer. Having Baal in your party you can actually chose to ally yourself with him, and he becomes a LEVEL 99 GOOD ALIGNED MAJIN WITH ALMOST MAXED STATISTICS AND GIVES YOU THE BEST SWORD OF THE GAME !  
 
You will then have to go back to Tokio, to the place where he was sealed. In a quite anticlimatic twist, the last dungeon is located behind the office of a CEO in the same dungeon where Lucifer was sealed. It isn't neither very long nor very difficult, with annoying but not very strong enemies. The semi-boss of this dungeon, Maoh Ashura, is converted automatically to Majin Ahura Mazda if you have Lucifer with you. The little fat CEO then reveals himself as Satan, and fights you, begrudging his previous servitude to Lucifer. After beating him , the chamber behind reveals a passage to a single corridor, where a voice emits very familiar threats. It's the dear old Mr. Bald Face.  
 
He asks you to betray Lucifer, but i haven't yet tried to respond YES and i've still to beat him.

Cool information

Well, Shinto is never ever mentioned in MTII (no Gaians here) and YHVH is as Old Testament-ish as he usually is , so its depiction is (once again) pretty accurate.

Weird how they elevate Masakados up above Amaterasu
Then again, they keep taking place in Tokyo, so...