The branching fraction of the decay Bs → Ds X has been measured by Belle and other experiments, but with indirect methods which have model-dependent limitations. We report a direct measurement of this decay by tagging one Bs from Y(5S) with semi-leptonic decay (Bs → Ds l nu), where several Ds decay modes are combined to increase the total statics. We also report a search for eta and eta' transitions from Y(5S) resonance to the lower bottomonia. These results are based on data sample of 121 /fb collected at the Y(5S) resonance by the Belle detector at the KEKB asymmetric-energy e+ e- collider. Other analyses on Bs and Y(5S) decays are also covered in this talk.