Nobunaga Concerto

The leads coming from a modern age end up back in time to the age of warring states, where samurai exists; and try to temporary live in such a world full of strife. They encounter, move the people around them, and fall in love. The only big difference is in Ashi Girl, it's the female lead; while in Nobunaga Concerto, it's the male lead.

In both, the main character had traveled through time and was forced to act as the lookalike imposter of the king from that period. He attempts to unify the kingdoms into one country.

In both, the husband/wife falls in love with the kind imposter while the real one tries to murder the imposter.

Genres: Action, Military, Historical, Comedy
Tags: Power Struggle, Sengoku Period, Oda Nobunaga, Adapted From A Manga, Time Travel, Honor Suicide, Doppelganger, Slight Romance, Hidden Personality, Deception

Both are about time travel back to the warring period of japan.
There are several more similarities but i would consider them spoilers.

Both of them are about high school students who travel back in time! The male lead in this drama is mistaken as a vassal while the female lead in Splash Splash LOVE is mistaken as an eunuch. Both dramas are light and sweet!