If you're looking for manga similar to Your & My Secret, you might like these titles. All recommendations are made by Anime-Planet users like you!
Both feature a body swap between a feminine guy and an unusual girl (in case of Boku to Kanojo no XXX she is a tomboy, but in case of Ani ga Imouto de Imouto ga Ani de. she is something different altogether). Needlessly too say both series are awfully similar and have this stench of shounen-ai\shoujo-ai, though Ani ga Imouto de Imouto ga Ani de. comes out as the more creepy one with the incest part (though between siblings not related by blood). If you liked one, then the other one should be right up your allay.
Eraser, the mysterious enemy that invaded Earth 13 years ago!! Before their overwhelming power, the entire Earth neared the verge of collapse. But at the last moment there suddenly appeared Earth's lone savior, The Beast: an ultimate weapon uniquely equipped to counter the Eraser's power!! The Beast is part of the MAGIC Brigade, whose commander-in-chief is also the founder of our Le Prince Academy.
Beast 9 is another body swap story where the main male character ends up in a girls body. Though there are only 20 chapters available right now, the story is getting interesting and has a slightly harem/ecchi comedy aspect to it. I would recommend checking this one out.