Board Thread:Questions and Answers/@comment-28196331-20161011050100/@comment-25942629-20161011130037

The anime shorts are not always canon and do not follow the original manga storyline. This scene does not occur in the manga. Additionally, these subtitles were written by -fans-, so they intentionally left enough astrics to fill in the word "homosexual." Whichever "creators" are being referred to by your source are probably not Takaya Kagami (male) and are therefore not the actual creators. Unfortunately, this information is completely false.

The anime also changed some things compared to the manga. For instance, Yu touches Mika's face after Mika bites him, they hug, and they even hold hands. These things don't happen in the manga. The weird forehead-contact opening definitely does not happen in the manga.

The anime tries very hard to ship them. It also changed their personalities, and they made Mika especially weak and clingy compared to the manga. It removed or alted the KrulxMika moments as well. The anime also had a couple of moments where they seemed to be shipping Yoichi and Kimizuki, which is quite strange.

So, in short, there is absolutely no confirmation on Yu's sexual identity, and the anime is absolutely not to be trusted!

...That said, there are more subtle hints in the manga that imply Yu may be in love with or at least completely obsessed with Mika, and Mika is not certain about what to do with this. Yu has absolutely no interest in girls. Even when he grabs Shinoa's hands and makes her flustered, he doesn't blush in the slightest or go out of his way to touch her later on. He only does this to make her agree to helping him save Mika. Later on, when Mika says Ferid was standing right next to him in Shinjuku and asks how Yu didn't notice their family's killer right in front of them, Yu says he never noticed because he could only see Mika. The anime had Yu fight Ferid in Shinjuku, but that never happened in the manga--Yu didn't care about Ferid but only about Mika. Yu's personality also changes drastically depending on Mika's well-being--he becomes much nicer once he finds out Mika is alive, and he has been completely fixated on Mika's death for the four years leading up to that. Additionally, Yu volunteered at least three times to have Mika drink his blood in one chapter alone when Mika started drinking everyone else's blood. He seems to like being bitten more than Mika likes biting.

I would say Yu has no evidence of being heterosexual. Whether he's homosexual, demisexual, or another kind of -sexual is hard to say at this point. Since he doesn't show signs of being attracted to any other males, I think it may be too early to call him homosexual. The game that was out for awhile on mobile had Yu praising Yoichi and Kimizuki's looks and saying he wanted a big family with Mika and all this crap, but that is absolutely not canon either.

http://nonbinary.org/wiki/Sexual_orientation <--Spectrum of attraction

All vampires are asexual by nature (suggested by the fan books and confirmed in Michaela light novels), so we've at least got Mika's sexuality covered.