The thing with secret casts is that they only seem to forbid the disclosure of their own. So if alien would say he is a vampire, vampire would say he is a wisard and wisard would say he is an alien - hypothetically nobody should be punished.
So it's like bikini and underwear' logic.
You may see girl in their bikini, because they wanted to show it off. But not underwear because it meant to be private thing.
Makoto's gotten better at making up tales on the fly. In an earlier chapter she tells Akira that she isn't good at lying (the hot springs chapter where they encounter the reporter) but she's apparently matured a little if she can come up with a fib like that.
I hope next chapter we get to meet the girl's family at long last😀