 If you liked Nana |  ...then you might like Mars |
Both are shoujo series that deal with romance and tragedy equally and have a more serious, adult tone. It's hard to be particular about it, but they both definitely have the same feel to them.
report Recommended by lithiumflower
Both are beautifully written, emotional, romantic dramas that tackle tragic events and appeal to more mature audiences despite being shoujo classics and Mars revolving around high schoolers. Both feature main characters that fight to pursue their passions (Nana Osaki with music and Rei with motorcycle racing) despite the challenges that come with them. The premises for Mars and Nana are otherwise very different, but they have a similar nostalgic, heartbreaking feel to them overall. If you enjoyed one of them and are looking for something with a similar vibe, I highly recommend the other.