Company Supertintin Co., Ltd created these great apps:
Echo Piano™, Echo Piano™ Lite, Echo Piano™ Pro, Echo String™, Echo String™ Lite, iGuzheng⁺ - Pro version, Echo Guitar™ Pro, MidiKey, iGuzheng, Echo Guitar™ Lite, Pitch Analyzer, iGuzheng Player, MIDILog, TextMusic, iSoundBank, TextMusic - Music Notation, NumScore - Music Notation, and others..