 If you liked
Liar x Liar
|
 ...then you might like
Imasugu Oniichan ni Imouto da tte Iitai!
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Both are romances between a step siblings, focusing around a big secret she's keeping from him.
Liar x Liar is a far longer and more serious manga than Imasugu Oniichan, though they share a lot in common, if you liked the antics and bro/sis pairing in one, you might like the antics and pairing in the other.