inconsistent sidebar

I changed themes (now using Ryan Simple) but it’s kept me busy ironing out the wrinkles.

My sidebar appears on SOME pages (“MACHIGAIって何？”, “BOOKS”), but not on the page “Tim先生と個人レッスン!”. I thought it might be because the text was in a table, so I got rid of the table but the sidebar still doesn’t appear. I’m guessing it must be something about the coding of the page. Or is it because this page is set as the home page?

The page I need help with: [log in to see the link]