Ai Kago, a fictional Japanese idol, has a 'Number 1 fan' - Kenta Yamaoka, initially a basketball player only, then a support American Football player.
History
In the anime, Hiruma, in his attempt to recruit players to participate in the spring tournament, reveals that Yamaoka kisses a big poster placed above his bed 'good morning' every day. Sources state that he also "spends 98% of his allowance to buy her CDs, products, and other stalking supplies".
Little more is known about her, except that she is presumably a middle school student, judging from her clothes and hairstyle.