Sei

Meaning: beacuse, due to

Related: okage, tame (ni)

Grammer: A dependent noun expressing a cause which brings about undesirable results

Formation

Kotoshi wa keizai no sei de kuruma ga amari urenai (Because of the economy, cars are not selling well this year)

nebusoku no sei ka karada ni chikara ga hairanai (Because of lack of sleep,I suppose, I feel weak (power does not enter into body))

Watashi ga しっぱい shita no wa kare no sei da

Examples

1) karou no sei de (because of overwork)

2) Hataraki-sugita sei de (Because of working too hard)

3) Kare wa yoku jibun no しっぱい o hito no sei ni suru (He often blames others for his own failure)