きつい, キツい
sometimes written 緊い
1. tough, hard, severe, demanding, harsh
2. determined, strong-minded, forceful, formidable, fierce
3. strong (e.g. sunlight, alcohol), intense
4. (too) tight, constricting, close
5. extreme, unusually strong
トムは頭にきつい一発を受けた。
のです, んです
Expression, の and ん add emphasis
the expectation is that ..., the reason is that ..., the fact is that ..., the explanation is that ..., it is that ...
お借りした車の調子が悪いのですが。