What is this 'Dimensional chat?'

My name Satria Akbar.

I just ordinary man in college with part time job but when I see kid almost got crashed by truck I save him and the result? yes I'am die.

I think my life finally over but somehow reborn in uknown world with new identity as Shidou Matsumi , Normal teenager with normal family.

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What the hell is this 'Dimensional Chat'