Restraining device, restraining assembly and seat unit

A restraining device of a seat unit, which seat unit further comprises a vehicle seat with a seating and a backrest, said restraining device comprising an airbag cushion being deployable to a deployed state, wherein said airbag cushion comprises a first part having a backrest-proximate first end, wherein in the mounted and deployed state

• said first part
• extends from its first end in a first direction over the shoulder of a person sitting in the vehicle seat to a backrest-distal second end being located in front of the person's head and/or torso, and
• extends in a second direction from a person-outer third end to a person-inner fourth end,
• wherein the airbag cushion additionally comprises a second part being connected to the first part, and a third part being connected to the first part and to the second part, wherein in the deployed state,
• said second part extends in a third direction from a fifth end to a sixth end and from a backrest-proximate seventh end to a backrest-distal eighth end, such that a least an upper section of said second part extends laterally of the person's head, and
• said third part extends in the second direction from a person-outer ninth end to a person-inner tenth end, such that at least an upper section of said third part faces the person's face.