This is a ticket forcan be used for five days as a free-to-ride on JRpass on regular JR trains, and one ticket can be used for five days.

Your sentence structure is grammatically correct but doesn't feel very natural :)

I have two more days left, so I'd like to go decided to go to Hamamatsu tomorrow.¶
OR I have two more days left, so I'm going to Hamamatsu tomorrow.

"I'd like" is used to describe hypothetical situations or to make a polite request. Here, because you say "I'm looking forward to it", it seems that it will definitely happen so you need a future meaning "I'm going" OR a decisive verb like "to decide" in the past to confirm that you are going.

There is a train ticket called " Seishun 18 kippu"."

This is a ticket for free-to-rideallows unlimited travel on JR regular JR trains, and one ticket can be used for five days.

I bought this ticketone this summer.

Here's thea sample picture of the ticket.

There is a type of train ticket called " Seishun 18 kKippu".

Just being more specific, and capitalising the whole name of the ticket

This is a ticket for free-to-allows for unlimited rides on JR regular trains, and one ticket can be used for five days.

I think "unlimited rides" is the best expression here

I bought thise ticket this summer.