Transfer from Keikyu Line to Asakusa Line

I want to go from Shinagawa Station to Tokyo Skytree. I also plan to buy subway 24-hr (or more) ticket. https://www.tokyometro.jp/en/ticket/travel/index.html

Google search tells me to take Keikyu Line from Shinagawa to Sengakuji. Then it says to remain on board and it will take me to Oshiage Station 13 stops later. Apparently, the Keikyu train turns into subway Asakusa train at Sengakuji Station. No transfer - that�fs great.

But how do I cover the cost of that trip using 24-hr subway ticket? Can I use it at Shinagawa Station to board the Keikyu Line?

The section between Shinagawa and Sengakuji is not covered. Therefore, you should buy a regular ticket from Shinagawa to Sengakuji at Shinagawa Station and use it to enter the station. At Oshiage Station you should be able to leave the station by inserting both your 24 hour pass and the Shinagawa-Sengakuji ticket into the ticket gate.