Tilde with hiragana-input I'd like to type the two characters "tilde" ('~') and "fullwidth tilde" ('～') with a german keyboard, since I need those characters quite often, for example when writing hiragana in romaji, for example 'っ' which is spelled ~tsu or song titles, for example "惑いて来たれ、遊惰な神隠し～Border of Death".

I tried the combination Alt+N, which produces '~' with the austrian keyboard map enabled, but does absolutely nothing in hiragana-mode.
Could you not create entries for keystrokes to generate these characters in the User Dictionary?  I think the Kotoeri Help tells how to do that in general.

Also you can make a wave dash by typing nami dasshu or part of it in Kotoeri and hitting space once or twice 〜