This is a Phase 2, single-arm, open-label (all knew the intervention of study), and multicenter (when more than 1 hospital or medical school team work on a medical research study) study to explore the efficacy, safety and pharmacokinetics (the study of the way a drug enters and leaves the blood and tissues over time) of ibrutinib in Japanese participants with relapsed (the return of a medical problem) or refractory (not responding to treatment) MCL. The study will consist of a Screening Phase of 30 days prior to first dose of study drug followed by treatment Phase and a post-treatment follow-up Phase. Participants will receive ibrutinib 560 milligram (mg) orally, once daily on a 28-day cycle until disease progression (or relapse if the participant achieved a CR), unacceptable toxicity, or study end, whichever occurs first. Treatment Phase will have disease assessments every 8 weeks up to 24 weeks after start of study drug, then every 12 weeks thereafter to assess efficacy up to 2 years after last participant enrolled. Efficacy will primarily be evaluated by ORR. Participants' safety will be monitored throughout the study.