Its currently in the top 3 i believe in japan.

The game has massive legs, already over 400k, it has tentencles! 

The notable games on home consoles releasin in 2015 are P5,Mario Maker,AC board game.

Well can Splatoon be #1?

In terms of individual platforms, absolutely.

If we combine platforms, it may be difficult with P5 or Dragon Quest Heroes, but still possible.

Yeah most likely.
I dont see persona 5 doing 800k by the end of the year(add to the fact it doesn't even have a release date yet).
MGS5 isnt going to be MGS4.
MM will probably sell 600k by the end of the year.
Now if they bundle Splatoon...
Thats a different story.

It certainly has a shot.

According to Vgchartz a Persona game has never hit the 400K mark for a game yet, let alone surpassed it.

Mario Maker should sell a ton though so it's hard to say. And AC is also up in the air.

It could definitely, not many other games will reach it's level by the end of the year, that said hom much did Xeno X sold by now in Japan ?

I'm thinking MGS V is gonna be a tough competitor

What about Youkai Watch 3? Or Metal Gear Solid?
Dragon Quest Builders has a chance too!

Dragon Quest Heroes is at 790k, this should be also very very hard thing for Splatoon.

In japan only? It could be. Just wait for the next Youkai Watch U. XD

Splatoon will easy outsell MGS, by a huge margin... by a smaller margin will beat Dragon Quest, but still will beat it.

Maybe just Yokay Watch 3 will sell more, but i'm not sure.

Yokai Watch 3 is Summer 2016 now, but it's not even a console game so that doesn't matter.

But yeah, I don't see MGS being a big obstacle really.