It's not just because of the female lead that they are similar, it's the way the whole drama was set. The plot, the cute second lead, the boss who hates but loves her at the same time. There's plot twists about the whole fate thing. The only difference I guess is that the mains aren't childhood friends but the main and the second leads are.
Both dramas are funny in their own geeky kinds of way and the actors in both dramas are great and both dramas both go well as they are similar in these areas.

It's a plot that revolves around friends, plot is different however a few similarities to know that they both kind of clash. If you think watching Unforgettable was a waterfall mayhem, ONe Way Trip won't disappoint.

The plot for both dramas are similar, about a couple who loses one another and in the end grow to love one another again. It's a drama worth watching, lot's of laughs and tears. And to top it off, a lot of idol actors too. Come on! Who would turn down Winner's Kang Seung Yoon?You'd be crazy if you did.

The mysteries in both plot storys, it makes you question so many things wrong with our society today. Corruption, why we murder.. The plots are 'somewhat' similar in terms of the genre and a bit of the character buildup but totally different in someway. Both dramas are a must watch, and will definitely not fail to please or surprise you.