I'm pretty sure that makes it clear enough already. BL isn't really requirement but both master and servant must be: MALES~

Can't remember all on the top of my head, but I've read(ing):
Kuroshitsuji
Cantarella
God Child & prequel
Vassalord
Silver Diamond
Rasen no Kakera
Noblesse
diece

Requirements:

• No ecchi, I've made it pretty obvious I'm female (I don't see how that would appear in here though o.O)
• No manhwa, I did list Noblesse but honestly I don't like reading manhwa
• No hardcore yaoi. I love BL, at a shounen-ai level. I do read yaoi as well, but nothing if the whole manga focuses on sex and nothing else
• Male lead: Duh! Both male master and male servants with BL as a plus

I'm looking for more of a loyal master-servant relationship, kinda like in Kuroshitsuji and Cantarella. But anything will do atm.

Hyakujitsu no Bara by Fusanosuke Inariya

The sex is pretty explicit but there is a strong plot.

“𝒯𝒽𝑒 𝓇𝑜𝓈𝑒'𝓈 𝓇𝒶𝓇𝑒𝓈𝓉 𝑒𝓈𝓈𝑒𝓃𝒸𝑒 𝓁𝒾𝓋𝑒𝓈 𝒾𝓃 𝓉𝒽𝑒 𝓉𝒽𝑜𝓇𝓃𝓈.” ― 𝑀𝒶𝓌𝓁𝒶𝓃𝒶 𝒥𝒶𝓁𝒶𝓁-𝒶𝓁-𝒟𝒾𝓃 𝑅𝓊𝓂𝒾.
あたしは腐女子です。少女漫画、たくさん読んでください。

Loveless Shounen ai
Pandora Hearts Shounen (Recommended)

I assume you might already be aware of the first two so another you might not know...

Wild Rose Yaoi (not hardcore) fantasy series 'Wild Rose' is book 2

💙💙💙💙💙💙

Quote from OtakuMadness

Loveless Shounen ai
Pandora Hearts Shounen (Recommended)

I assume you might already be aware of the first two so another you might not know...

Wild Rose Yaoi (not hardcore) fantasy series 'Wild Rose' is book 2

Oh... i forgot about Loveless. feels dumb

“𝒯𝒽𝑒 𝓇𝑜𝓈𝑒'𝓈 𝓇𝒶𝓇𝑒𝓈𝓉 𝑒𝓈𝓈𝑒𝓃𝒸𝑒 𝓁𝒾𝓋𝑒𝓈 𝒾𝓃 𝓉𝒽𝑒 𝓉𝒽𝑜𝓇𝓃𝓈.” ― 𝑀𝒶𝓌𝓁𝒶𝓃𝒶 𝒥𝒶𝓁𝒶𝓁-𝒶𝓁-𝒟𝒾𝓃 𝑅𝓊𝓂𝒾.
あたしは腐女子です。少女漫画、たくさん読んでください。

Angel Sanctuary - the villain and his servant are both males (though the villain looks very feminine)

[img]http://oi50.tinypic.com/1p7xj6.jpg[/img]