Well what exactly is your problem? Are you having a problem with grammar, vocab, or kanji?
I’d imagine it’d be all 3 after textfugu because it really doesn’t take you that far. You’re not really going to find a one stop place to learn Japanese so you need to supplement everything you do with something else.

For grammar You can go the textbook route (Genki1/2 and Toriba/An integrated approach to intermediate Japanese) Or Tae Kim.

For Kanji you can do remembering the kanji or Wanikani (I personally use wanikani so i’d recommend that one more but i’m biased :p)

For vocab you should do core 2k/6k

Tobira is an awesome textbook but it would be way too hard for someone who’s only done TextFugu. I’d say have a look at Tae Kim’s grammar guide, or maybe some other beginner textbook like Genki or Japanese for Busy People, since TF covers so little. Read some simplified news articles on http://www3.nhk.or.jp/news/easy/index.html too, those are good. Try out Core 6k on Anki for learning new words.

Not an exhaustive list but just a few good resources I recommend :)

We studied two-thirds of Tobira in my third-year Japanese course. Still need to study the other third of it sometime. And finish the third book of Japanese for Busy People. And finish Tofugu…

But yeah, Tobira’s almost completely in Japanese. Only uses English to define new kanji and explain new grammar.

@Cimmik: It depends how you define “level”. Your grammar and vocab and general reading skills will improve with such courses, but listening/speaking/writing won’t. Don’t pick the one that takes you to the most advanced level once you’re through with it, pick one that starts at an appropriate level for where you’re at just now and that is enjoyable. Tae Kim might have more content than Genki, but if you prefer Genki and find it easier, try it first.

Yeah, I guess they both start from the beginning. My main point is to pick the one you like better, not necessarily the one with most content. Better yet, pick as many different resources as you can and get the good parts of all of them :D Read Tae Kim *and* Genki *and* Japanese for Busy People *and* whatever else you can get your hands on – the more different explanations, the easier it will be to understand stuff. Having said that, Tae Kim is pretty good and it’s free, so I’d probably start there if you don’t have infinite money (or a lack of morals).