The purpose of this study is to describe the initial response to ustekinumab induction treatment for ulcerative colitis (UC) in Japan.

Inclusion Criteria:

• Must have a confirmed diagnosis of ulcerative colitis (UC) in accordance with local practice
• Has a current UC severity that is judged by the treating physician to be moderate to severe (being a partial Mayo score of 5 to 9, inclusive)
• A decision has been made by the treating physician and the participant within routine clinical practice to commence treatment with ustekinumab, having been deemed to have an inadequate response to, or intolerant to, previous UC therapy
• Must sign an informed consent form (ICF) allowing data collection and source data verification in accordance with local requirements. If the participant is 16 to 19, informed consent might be obtained from each study participant according to the regulation of institution/hospital and their legally acceptable representative must sign an ICF
• Must be able to read, understand, and complete participant-reported outcome instruments, and intend to cooperate with completion of participant-reported outcome instruments using smartphone/tablet

Exclusion Criteria:

• Has ever previously received ustekinumab (including clinical trial use)
• Are currently receiving, or have received within the past 3 months, systemic treatment with a biologic therapy for any other indication (example Crohn's disease, psoriasis, rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis)
• Received an investigational drug (including investigational vaccines) or used an invasive investigational medical device within 3 months before the start of the study or the first data collection time point
• Currently enrolled in an interventional study or another Janssen-sponsored observational study (including post-marketing surveillance)
• Based on physician judgement has i) severe extensive colitis and is at imminent risk of colectomy OR ii) a stoma or history of a fistula OR iii) previously had extensive colonic resection (example, less than 30 centimeter (cm) of colon remaining) OR iv) current fulminant colitis OR v) currently hospitalized for worsening of UC-related symptoms (not excluded if the reason for hospitalization is first dose of ustekinumab)

Study population will consist of participants who have had previously inadequate response, or have been intolerant to, conventional or biologic therapies and will be initiating ustekinumab for their ulcerative colitis.