Delicious in Japanese is "oishii" The proper way it is written is "美味しい" The hiragana version is "おいしい" To say "This is delicious" you say "Kore wa oishii desu"...
well, due to it being a foreign word to Japanese katakana is used but sound sounds like " Co-he-" the dashes represent elongated tones. If you wanted to say, "Do you want coffee?", you would say...