Oishii おいしい
You may say 'oishii' or 'umai.'
"Ko-hi- ga oishii desu" (pronounced: KOH-HEE gah oy-shee dess). コーヒーがおいしいです。
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"...
You may say 'Sugoku/Totemo oishii desu.'
"Oishikatta" (pronounced: oy-shee-KOT-tah). おいしかった