  We have revisited the possible existence and the binding mechanism of heavy
hyperhydrogen 6^H_Lambda. This Lambda hypernucleus is enriched in information
about Lambda hypernuclear dynamics which would shed a light on significant role
of coherent Lambda-Sigma coupling effect in neutron-rich nuclear medium,
discussed by the authors. Recently, reports on an experimental evidence of
6^H_Lambda with theoretical comparison have appeared, wherein the significance
of the coherent coupling in 6^H_Lambda has been criticized. In this report, we
are revising our previous work and give further theoretical analysis to confirm
the influence of the Lambda N - Sigma N coupling effect in the binding
mechanism of 6^H_Lambda.
