Sage Naruto appears more frequent in events so you don't have to worry if you think it appears only for this week. The cost of sage naruto is different in every event. Tenten appears in events too like Naruto.

Limited Time recruitment usually appears on the 4th week of any given month. Lukcy for you, that's next week. It is an event where you use stamina on plot/elite instance and you get points for it. You c*so use coupons/ignots to get points. You use these points to recruit ninjas.

If you really want to use tenten, she is well suited for water main. However, if you only want to be fire main, be prepared to see unfavorable results.