Original Work
noun, の adjective
The original thing you make is the original work. It's always better to have the original, rather than a copy, I think.
げんさく
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
マンガが原作の映画は、原作の良さを失ってしまうことが多いです。
Comic book movies often lose the flavor of the original work.
シェイクスピアを原作で読んだことはありますか？
Have you read Shakespeare's original works?
この漫画は、テレビアニメとドラマの原作です。
This manga was made into a TV anime and drama series.