To get to Kanto in Pokemon Let's Go Pikachu/Eevee, you'll need to pass through Victory Road in the Indigo Plateau. Once you reach the end of Victory Road, you'll encounter a man called Lorelei blocking the entrance. After you defeat her in a battle, she will step aside, allowing you to pass into Kanto.
She will not let you pass to the Kanto Region where victory road is until you battle the Kimono girls in the Dance Theater and either capture or defeat Lugia.
You need to catch Luiga or Ho-oh before you go to Kanto. (personally I don't know why but it's in the game)
catch lugia
cheat
you go to lyra in your house after you get all the gym bages in kanto and talk to her and there will be a earth quake
After you defeat kanto league go to professor elms lab and talk to him,he will give you the SS Aqua pass to go to kanto and you go;after that defeat all the kanto liders.
a
Beat the elite four. Professor Elm, I think, someone, will give you the boat pass for the harbor in Olivine, which will take you to Kanto
You can't
You can now use the train from kanto to johto.
Beatriz Lyra's birth name is Beatriz Alcina de Lyra Andrade.
The constellation between Cygnus and Hercules is Lyra. Lyra is represented as a harp in Greek mythology and contains the bright star Vega.