Ayumis secret, a real tattoo.

This whole thing is very interesting! I'm not quite sure how true this is, however, considering the original quote by "Ryan Chan" has been removed from the site (it is possible someone posed as him).

However, if it is true, it gives validity to the gossip article that Ayumi & Tomoya had matching tattoos done and did have a dual photo session.

On the covering up tattoos with make-up, it's VERY difficult. Even on tv, covered tattoos are visible on celebrities in the right light. The only way to really cover it up well is with an additional covering (like a fake layer of skin) in addition to just regular concealer. But that's really going the extra length to hide body art.