This is from Riida's interview with Tetsuko Kuroyanagisan in Tetsuko no Heya aired February 13, 2009.
Tetsukosan appeared twice in Ohno's "Uta no Oniisan" as, I think Tetsukosan herself where Kenta Yano's dad bumped into her along the hallways of the Tv station where he was working at. And at the end, she appeared again along the hallways of the same tv station bumping into Kenta Yano, I guess.
How do Arashi normally call each other?
Sho - "Shokun"
Jun - "Matsujun"
Nino - "Nino"
Aiba - "Aibachan"
and how do they call him?
Ohno - "Riida", "Captain", "Ochan"
* some trivia: Ohno is called "Satoshi" by his family, and the name means "wisdom, intellect, reason". Hmmm... I'd bet the rest of Arashi will die of laughter before they even say the whole "Satoshi" word to refer to their captain. ^^,
* when they were in Taipei, he (and the others, I suppose) sorta somehow got themselves a new hobby of calling Aibachan just "AIBA!", yeah in capital letters. lol. Coz from what I understood, they didn't actually just call Aiba by his name, but they yelled at him. lol. "AIBA! AIBA!". Awww... poor Aiba. ^^,
During that time too, the other members used "Ochan" to refer to him. ^^,