The /ʃ/ sound is spelled with <sh> and <ch> in chaise. The /j/ sound is spelled with <y> and occurs in the letter name U.
This is a contrast between a voiceless alveolar fricative and a voiced palatal semivowel. It can only occur initially or medially. It is not a problem.
The mean density value is 0.6%. The lists make 24 semantic distinctions, a loading of 59%.
chaise yeas shack yak shacks yaks shah yah sham yam shams yams shank yank shanks yanks shanked yanked shanking yanking shard yard shards yards shawl yawl shawls yawls she ye shear year shears years sheer year shell yell shelled yelled shelling yelling shells yells shield yield shielded yielded shielding yielding shields yields Shirley yearly shoe U shoes U's shone yon shore yaw shores yaws shored yawed shore yore shores yours shorn yawn shot yacht shots yachts Shotts yachts showman yeoman sure your
John Higgins, Shaftesbury, December 2010.