Oh, this comment reminded me that I'd meant to point out some other Nobuta stories that you might like. They're mostly gen and het and femslash, as well as a few Shuuji/Akira stories that I think include Nobuta in interesting and good ways:

Pattern Recognition by asinful (Akira/Nobuta)
Ugly Ducklings by bookshop (Shuuji/Akira)
Five Things That Changed Since The Last Time Nobuta Saw Shuuji and Akira by ilanabean42 (Shuuji/Akira)
How to Keep a Friend by ilanabean42 (Akira/Nobuta)
Untitled by ilanabean42
Sweets to the Sweet by Mayhap
Stars by mindlint
Untitled Nobuta/Mariko by one_if_by_land
Speed of Light by Pero
Confession Version 2.0//Akira SHOCK(ed)!//Summertime by saxon_dogs (Shittaka/Nobuta) -- You haven't mentioned Shittaka that I've seen, but I think he's adorable, and Nobuta's great in this.
Dear Shuuji by Shay (Shuuji/Akira and Nobuta/Mariko)
Good Luck Pig by shrift (Shuuji/Akira)
Untitled One-Sentence Set by sivullinen (Shittaka/Nobuta)
For a Season by the_suit_case
It's Gonna Rain Tomorrow by walkwithheroes (Akira/Nobuta)
Modern Courtship by walkwithheroes (Akira/Nobuta)
Nobuta in Blue by walkwithheroes (Akira/Nobuta)
Separately, Together Part 1 and Part 2 by walkwithheroes (Akira/Nobuta, Shuuji/Mariko)
Eye of the Storm by waxrose (Shuuji/Akira)
Guilt Free at Three AM, Warmer Together, and The Morning After by wintersjuly (Shuuji/Akira/Nobuta) -- I can't remember how you feel about threesomes, but regardless, I think you'd like these stories. They have very much the feeling of the series to me: romantic friendship might be the best way to describe their relationship here.
Untitled Akira/Nobuta by wintersjuly
Untitled Nobuta/Bando by yamapea