The thing about including knights is that knights don't have a readily available database, like the senshi do on their cellphones. c: Where senshi can find out about the programme on their own and contact a mentor/sign up as a mentor through their phone, knights have no such option; they do have their rings, but they'd still have to hear about it from someone else and get the info about who's available as mentors, etc, from an actual person as well. The only thing I can really think of for them is a sort of chain-letter, and of course advertising the mentoring programme by mouth.
Or, and this is a bit complicated, possibly Vanadis ICly asking other characters to keep an eye out for interested knights and get back to her with their names; she could team up with a knight to send them the info for the programme, only in print instead of online, as well as her contact information and get the interested knights the full information as well as a way to get in contact with possible mentors / students, with Vanadis as a middleman if needed. Would that work, or is it too complicated?
