This article tells you how to travel from Haneda Airport to Shinagawa Station.
From Shinagawa you can take the Shinkansen to the Kansai area.

The reason for using the Keikyu Line is that using the Keikyu Line to travel from Haneda Airport to Shinagawa Station is a reliable, convenient, cost-effective and fast way to travel.

・How to get on
There are three ways to get on the Keikyu Line: by buying a ticket, by using a transport IC card or by using a mobile transport app. Mobile Suica is the easiest, most convenient and recommended, but you can use whatever method you prefer.
To know about it, check other my blogs for more information.

• How To Purchase Welcome Suica at Haneda Airport Terminal No.3
• Where can we buy Suica card? And which one is better, IC card or Mobile App?

・Cost and the time required
It takes 12 minutes to reach Shinagawa on the limited express train and 21 minutes on the express train.

The fare is 327 yen if a transport IC card or Mobile transport App is used,
330 yen if the ticket is purchased from a ticket vending machine. These are one-way prices.

・Operating Time
The first train departs at 5:26 am and the last train departs at 23:51 pm.
Please take into account the time your flight arrives if you can make it in time.

There are several types of train are operating, Local（普通）, Express（急行）, Limited Express（特急、快特）, Airport Limited Express（エ快）.

・Important point

品川方面 stands for this train go for SHINAGAWA, 
横浜方面 stands for this train go for YOKOHAMA.

Make sure you had better check the directions after Keikyu kamata station, which go to Shinagawa.
If you notice that the next station after keikyu kamata is Umeyashiki(KK10), 梅屋敷 in Japanese, it will go to Shinagawa, on the other hand,
if you find that is Zoshiki(KK18), 雑色 in Japanese, it won't go to Shinagawa. You have to transit an other train to change the direction. Please have a look at the below image. It would helps you understand.

Enjoy your wonderful trip to Japan(^^